Overview

The silver arowana, Osteoglossum bicirrhosum, is one of the best known representatives of the ancient family Osteoglossidae. Fossils show that its ancestors already lived in the Jurassic period, around 150 million years ago. These primitive bony-tongued fishes once inhabited rivers of the supercontinent Gondwana, which later split into South America, Africa, Australia and Southeast Asia. This explains why closely related arowana species are now found on several different continents. Despite its popularity, the silver arowana fish is considered difficult to keep. Its very large size and strongly carnivorous diet mean that only experienced and usually well-funded aquarists can provide proper conditions. Juveniles are often sold at an affordable price, but many buyers underestimate how quickly the fish grows and how much space an adult requires. As a result, grown specimens are frequently rehomed when they outgrow their original aquariums.

Habitat

In nature the silver arowana comes from the Amazon River basin in South America, including many of its tributaries. During the dry season it prefers regions with slow current, backwaters and lagoons. With the arrival of the rainy season the fish moves into flooded areas of tropical forest, using the newly formed channels among the trees to search for food. This lifestyle, alternating between open water and submerged forest, has shaped many of the species’ behavioral and anatomical adaptations.

Description

Adult silver arowanas reach 70–80 cm in length. The body is long and streamlined, while the dorsal and anal fins run from the middle of the body all the way to the tail, forming a single large “fan”. This structure allows the fish to accelerate rapidly when hunting and to perform powerful jumps. The most characteristic feature is the structure of the mouth. It opens upward and is perfectly adapted for taking prey from the water surface. On the lower jaw there are two bony extensions, which are reflected in the scientific name of the genus: “Osteoglossum” can be translated from Greek as “bony tongue”. The overall appearance of a grown silver arowana is very impressive, and in large aquariums it quickly becomes the dominant centerpiece fish.

Unique features and physiology

The upturned mouth and elongated body are directly linked to the hunting style of this freshwater predator. In the wild the silver arowana watches for prey not only in the water but also above it. It is capable of spotting insects or small animals sitting on leaves, branches or tree trunks that hang over the water and then leaping up with surprising accuracy to catch them. This ability to jump high out of the water is one of the reasons the species is so famous among aquarists.

Although primarily a carnivore, the silver arowana also consumes plant material such as fruits and other tree-borne items that fall into the water. Its jaws and digestive system are adapted to a varied but protein-rich diet. In addition, silver arowanas form clear hierarchies, with dominant individuals controlling specific stretches of water and keeping other arowanas away. This territorial behavior strongly influences how they behave in captivity.

Feeding

In the wild the silver arowana hunts fish and insects, including many that are not strictly aquatic. It patrols the surface, waiting for movement, and can suddenly rush forward or jump upward to seize its prey. This hunting strategy should guide the diet offered in the aquarium. The basis of the diet in captivity can consist of shrimp, mussels without shells, earthworms, various insects and pieces of fish. Some keepers also offer live fish, but this is not essential if a varied range of meaty foods is provided. Plant components, such as pieces of fruit, may be accepted as well, reflecting the natural diet of the species. High-quality, fresh foods help maintain strong health, growth and coloration. Because of the fish’s size and active lifestyle, feeding must be consistent and well planned.

Care and Aquarium Setup

Silver arowana care is only realistic in very large and tall aquariums. For a single adult, the recommended silver arowana tank size starts from 1000 l. Such a tank must be equipped with powerful filtration systems and other specialized equipment able to handle the considerable biological load produced by a large predatory fish. Aquariums for this species are often arranged as natural biotopes resembling the Amazon. Typical decorations include numerous large driftwood pieces, a bottom covered with fallen leaves and overhanging vegetation above the water surface, combined with a few floating plants. The choice of substrate is not critical; the fish can live over sand, fine gravel or other materials, as long as they do not injure the arowana. Lighting is usually dim to moderate, and water movement should remain weak to moderate so as not to exhaust the fish.

Due to the impressive jumping ability of silver arowanas, aquariums are normally built high and kept securely covered. In practice, display tanks of this size are expensive and are often installed and serviced by professional companies, while the owners simply enjoy the result. For this reason, detailed step-by-step guidance on building such systems is usually beyond the scope of general hobby literature, and this article focuses on the main requirements only.

Behavior and Compatibility

In their natural habitat silver arowanas show a pronounced social hierarchy. A dominant fish controls a particular stretch of water and does not allow other arowanas to enter its territory. The same pattern frequently appears in captivity. When two or more individuals are kept together, serious fights can occur as they compete for dominance. Therefore, keeping multiple silver arowanas in one aquarium is risky and requires extremely large volumes. Community setups are only possible with species of comparable size that will not be seen as prey. Examples include pacu or large Amazonian catfish. It is advisable to avoid species that live in the upper layers of the water column, as they may directly compete with the arowana for territory near the surface and provoke aggression. Small and slow fish should never be housed with this predator, as they are likely to be eaten.

Breeding

During the breeding season an adult female silver arowana lays between 50 and 250 eggs. In practice, the number of youngsters that survive to the free-swimming stage is much lower, and a typical brood contains about 12–30 juveniles. The young are relatively large, reaching about 7 cm in length, and are often sold in shops at this size. Breeding silver arowanas in the home aquarium is rare and associated with many difficulties, mainly because of the enormous tank size, compatibility issues and the need to manage aggressive adults. Commercial fish farms are far more effective at producing healthy offspring, and most fish on the market come from such facilities rather than from private breeders.

Health and diseases

The silver arowana is generally hardy and undemanding if its basic environmental needs are met. It does not suffer from any unique, species-specific diseases. Most potential health problems are linked to husbandry: poor water quality with elevated concentrations of toxic nitrogen compounds, unsuitable pH or hardness values and other stress factors. Maintaining stable conditions within the recommended range, along with regular water changes and careful monitoring, is the best way to prevent disease. If symptoms do appear, treatment should follow general guidelines for aquarium fish illnesses.

Conclusion

The silver arowana is an ancient and impressive predator that offers a unique glimpse into the evolutionary history of freshwater fishes. Its large size, surface-oriented hunting style and striking appearance make it a dream species for many enthusiasts. At the same time, it demands enormous aquariums, strong filtration, a carefully planned diet and thoughtful selection of tank mates. For aquarists who can meet these requirements, keeping this large freshwater arowana can be a rewarding long-term project. A healthy, well-maintained silver arowana gliding under dim light in a spacious Amazon-style aquarium is an unforgettable sight and a true highlight of any serious fish collection.

Overview

The Asian Arowana, Scleropages formosus, is one of the most famous and expensive ornamental fish in the world. It belongs to the ancient family Osteoglossidae and is often associated with the so‑called “dragon fish” in East Asian culture. Due to its resemblance to the Chinese dragon, a symbol of prosperity and good fortune, the species has become a status symbol and is highly prized by collectors.

Because of heavy fishing pressure and habitat loss, wild populations of Asian Arowana declined sharply, and the species is now listed on CITES and protected by law. Wild‑caught export is prohibited, and fish sold for the aquarium trade come from licensed farms that breed the species in captivity. Each legally farmed specimen carries an individual microchip and certificate to confirm its origin.

Habitat

Asian Arowanas are distributed across much of Southeast Asia, including parts of Malaysia, Indonesia and surrounding archipelagos. They inhabit slow‑moving or standing waters such as blackwater rivers, forest streams, flooded forests, backwaters and swampy lakes. These habitats are typically shaded, with overhanging vegetation, submerged roots and branches.

The water in their natural environment is usually warm, soft and slightly acidic, enriched with humic substances from decaying plant material. In the aquarium it is recommended to provide similar conditions: clean, well‑filtered water with stable parameters, moderate lighting and some driftwood, branches and plants to create shaded areas.

Description

Adult Asian Arowanas can reach around 90 cm in length. They have an elongated body, large pectoral fins and dorsal and anal fins set far back toward the tail. Compared with the Silver Arowana, the caudal fin is larger and more rounded. The scales are very large, each one reaching up to 2 cm in diameter, and form clearly visible rows along the body.

The coloration varies widely depending on the geographic form and selective breeding. Common varieties include green, silver, golden and several red forms, with the red and gold strains being especially valuable. Strong, even colour and clean scale pattern are highly prized traits in the ornamental fish trade.

Behavior and compatibility

In the wild Asian Arowanas are surface‑dwelling predators that patrol the upper water layers, often staying near overhanging vegetation and submerged structures where potential prey may appear. They are most active at dusk and during the night. In captivity they are territorial and generally kept singly to avoid aggression.

Suitable tank mates include large, robust bottom dwellers or mid‑water fish that are too big to be swallowed, such as large catfish or some big characins. Small fish are quickly eaten, and similar surface‑dwelling predators may compete for space, so such combinations are best avoided.

Care and aquarium setup

Asian Arowanas require very spacious aquariums of 1000 litres or more, with a long footprint and secure, tight‑fitting cover. These fish are powerful jumpers and can easily exit the tank if given the chance. The décor should provide open swimming space at the surface, with vertical pieces of driftwood and roots breaking up the line of sight and adding a natural feel.

Soft, slightly acidic water enriched with tannins is considered ideal. This can be achieved using peat, leaf litter or commercially available blackwater extracts, as well as natural décor pieces such as bark and dried leaves. Filtration must be strong and reliable, and regular water changes are crucial, because large carnivorous fish produce considerable waste.

Feeding

The long‑term health of Asian Arowanas depends heavily on a properly varied diet. In the wild they prey on fish, insects, amphibians and other animals that fall or move near the water surface. In captivity they should be fed live or frozen foods such as shrimp, crickets, mealworms, earthworms, feeder fish from safe sources and other similar items.

Many farmed fish are trained to accept high‑quality floating pellets for large carnivores, which can be used as part of the diet. However, just like with the Silver Arowana, mammal and poultry meat should be avoided due to inappropriate fat composition. A varied menu helps support strong colour, proper growth and a robust immune system.

Overview

Aristochromis christyi is a large predatory cichlid from Lake Malawi in East Africa. Despite its hunting nature it is relatively calm toward fish of similar size and can be kept successfully in spacious Malawi community setups. The main limitation for this species is its size and the very large aquarium required for long‑term care.

For aquarists who can provide the necessary space, this cichlid offers interesting behavior and a striking appearance. Males in breeding condition display beautiful blue tones, while females are more modestly coloured but still attractive. As with many Malawi cichlids, a group consisting of one male and several females works best.

Habitat

In nature Aristochromis christyi is found throughout Lake Malawi. It prefers so‑called intermediate zones where rocky shorelines gradually give way to open sandy areas with scattered rocks. These transition zones offer both cover and open space for hunting.

The water in Lake Malawi is warm, alkaline and mineral‑rich. It is very stable in terms of chemistry and temperature, and this stability should be mirrored in the aquarium. Sudden changes in parameters are poorly tolerated by most Malawi cichlids, including this species.

Description

Adults reach 25–30 cm in length and have an elongated, muscular body. The head is large with a wide mouth, clearly indicating the predatory lifestyle of the fish. The dorsal and anal fins are set far back toward the tail, providing powerful bursts of speed when chasing prey.

Males show shades of blue on the body and fins, especially when ready to spawn, while females are generally greyish and somewhat smaller. Both sexes typically have a dark horizontal stripe running from the head to the tail, though in dominant males this stripe can fade during courtship displays.

Feeding

In the wild Aristochromis christyi is an ambush predator that feeds primarily on smaller fish. It may stalk prey among rocks or over open sand. One observed hunting strategy involves the fish approaching slowly and then suddenly lunging at an unsuspecting victim. Another involves lying on its side near the bottom, pretending to be dead until small fish come close enough to be attacked.

In the aquarium it does not need to be fed live fish. A diet based on high‑quality meaty foods such as shrimp, mussel meat and pieces of fish is sufficient. Occasional use of quality pellets or sticks for large cichlids helps to provide vitamins and trace elements. Overfeeding and fatty mammal meats should be avoided to prevent digestive issues.

Care and aquarium setup

A single adult Aristochromis christyi needs at least 500–600 litres of water, and significantly more if kept in a group. The aquarium should offer both open swimming space and rock structures that create territories and hiding places. A sandy substrate is recommended to mimic the natural lake bed and to protect the fish when it digs or rests on the bottom.

Filtration must be strong and efficient, as large predatory cichlids produce substantial waste. Regular maintenance, including partial water changes and removal of detritus, is essential. Water parameters should be kept close to those of Lake Malawi: warm, alkaline and hard, with minimal fluctuations.

Behavior and compatibility

Although predatory, this species is not overly aggressive toward similarly sized tank mates. It can be kept with other large Malawi cichlids and robust species that share similar water requirements, as long as there is enough space and hiding places. Any fish under about 10 cm should be considered potential prey and is not suitable as a companion.

In smaller tanks it is best to keep a single male with several females. Males are strongly territorial and will fight each other, especially in confined spaces. In larger aquariums with plenty of rockwork, aggression is easier to manage but should still be monitored.

Breeding

Breeding is possible in very large aquariums but requires experience and careful planning. The species is a maternal mouthbrooder: the female incubates the eggs and fry in her mouth for several weeks. A harem structure with one male and multiple females helps distribute the attention of the male and reduce stress on individual females during courtship.

Overview

The Myanmar Arowana is a very rare and expensive variant of Asian arowana. In the trade it is sometimes referred to as Scleropages inscriptus and is prized for its complex scale pattern and limited natural range. Like other arowanas, it is a powerful surface-dwelling predator and requires a very large, carefully planned aquarium.

This species is not suitable for beginners. High purchase price, strict legal regulations in many countries and demanding care requirements mean that only experienced keepers with enough space and budget should attempt to keep a Myanmar Arowana at home.

Habitat

In nature Myanmar Arowanas occur in a limited area of Myanmar (Burma), in slow-flowing rivers and floodplain areas with warm, soft, slightly acidic water. The shores are often densely overgrown with vegetation, and the fish patrol the surface looking for insects, small fish and other prey.

Seasonal flooding creates large, shallow areas with submerged roots and branches. During the dry season fish retreat to deeper channels and pools, but they still stay close to cover such as driftwood, fallen trees and dense shoreline plants.

Description

Myanmar Arowanas have the typical elongated, laterally compressed body of all arowanas, with a large upturned mouth and long dorsal and anal fins placed far back towards the tail. The scales are large, metallic and often decorated with darker “inscriptions” or irregular markings, which gave the species its Latin name.

In the aquarium they can reach 60–70 cm in length. Juveniles are usually more colourful, with contrasting edges on the scales and fins. With age the pattern becomes more subtle, but adults still look very impressive and quickly become the visual center of the tank.

Feeding

In the wild Myanmar Arowanas are opportunistic predators that feed on smaller fish, crustaceans and large insects that fall on the water surface. In captivity they should receive a varied diet based on meaty foods. Suitable options include pieces of fish and shrimp, earthworms, nightcrawlers, frozen prawns and high-quality carnivore pellets.

Feeding warm-blooded meat (beef, chicken, pork) is not recommended because the fat composition is unsuitable for fish and may lead to liver problems. It is also better to avoid feeder fish of dubious origin to reduce the risk of parasites and infections. Offer relatively small portions and remove uneaten food to keep the water clean.

Care and aquarium setup

A single adult Myanmar Arowana needs a tank of at least 1000 liters, and more is always better. The aquarium should be long and wide so the fish can turn around and swim comfortably. Keep the tank tightly covered; arowanas are powerful jumpers and can easily knock off loose lids.

Use sand or fine gravel as a substrate and decorate the tank with large pieces of driftwood and sturdy plants along the sides and back, leaving a lot of open swimming space near the surface. Strong filtration, regular water changes and stable warm temperatures are essential, because this species is very sensitive to poor water quality.

Behavior and compatibility

Myanmar Arowanas are solitary, territorial predators. They usually ignore tankmates that are too large to be swallowed but will hunt any smaller fish. Keeping several arowanas together is risky and often leads to aggression except in enormous, carefully managed tanks.

Possible companions include other large, robust fish with similar water requirements, such as big catfish or large cichlids. Even in such combinations the behavior of the arowana should be monitored closely, especially during feeding, to avoid injuries and chronic stress.

Overview

The African Pike (Hepsetus odoe) is a long, torpedo‑shaped predator from African rivers. In the aquarium it is known for its speed, powerful strikes and impressive size. Despite the common name, it is not a true pike but a characiform fish from the family Hepsetidae.

This species is kept almost exclusively by experienced aquarists who can provide a very large tank, strong filtration and a carefully chosen community of robust tankmates. Any fish small enough to fit in its mouth will eventually be eaten.

Habitat

African Pike inhabits slow to moderately flowing rivers, lakes, backwaters and floodplains across much of tropical Africa. It prefers warm, slightly acidic to neutral waters with plenty of submerged wood, aquatic plants and overhanging vegetation that provide cover for ambush hunting.

During high water seasons the fish follow migrating prey into flooded forests and grassy margins. When water levels drop they return to deeper channels, staying near structure where currents are weaker.

Description

African Pike have an elongated, streamlined body, pointed snout and large mouth filled with sharp conical teeth. The colour is generally silvery to olive‑brown with darker mottling along the flanks, which helps camouflage the fish among roots and vegetation.

In nature they can reach up to 70 cm in length, although most aquarium specimens stay somewhat smaller. The dorsal and anal fins are set far back, providing explosive bursts of speed when attacking prey.

Feeding

In the wild African Pike feed mainly on smaller fish and occasionally on crustaceans and other aquatic animals. In captivity they should receive a diet based on high‑quality meaty foods: pieces of fish and shrimp, earthworms, krill, large insect larvae and suitable frozen foods.

Feeder fish should be avoided unless you are absolutely sure they are healthy and quarantined, as they can introduce parasites and disease. Overfeeding quickly leads to water quality problems, so feed moderate portions and maintain regular water changes.

Care and aquarium setup

A single adult African Pike needs at least a 500‑liter aquarium, and larger is strongly recommended. The tank should be long, with a tight‑fitting lid, as this species can jump when startled. Provide open swimming space in the middle and upper levels, with driftwood, roots and hardy plants along the sides for cover.

Filtration must be powerful, with stable temperature and clean, well‑oxygenated water. Strong currents are not necessary, but a gentle flow that prevents dead spots is beneficial.

Behavior and compatibility

African Pike are solitary ambush predators. They can co‑exist with other large, fast and robust fish that are too big to swallow, but small or slow tankmates will be viewed as food. Territorial aggression may occur, especially in cramped tanks.

Do not keep them with delicate species or fish that stress easily. Observe interactions carefully, particularly during feeding, to ensure that all fish receive food and no one is constantly chased or injured.

Overview

The African Snakehead (Parachanna africana and related species) is an air‑breathing predator from West and Central Africa. It is more compact than many Asian snakeheads, but still powerful and capable of serious damage to tankmates.

Because snakeheads can survive in low‑oxygen water and even breathe atmospheric air, they are hardy fish, but their predatory nature and need for secure lids make them suitable only for keepers who understand their behaviour.

Habitat

In nature African Snakeheads inhabit slow rivers, swamps, floodplains and heavily vegetated pools. The water is usually warm, soft to medium hard and often stained brown by tannins from decaying leaves and wood.

During dry seasons some snakeheads can survive in shallow, oxygen‑poor waters thanks to their accessory breathing organ. They often stay near submerged roots, dense plants and other cover from which they ambush passing prey.

Description

African Snakeheads have elongated bodies with long dorsal and anal fins and a slightly flattened head that resembles that of a snake, hence the common name. Colouration varies from light brown to grey with darker bands, blotches or chevron‑shaped markings along the sides.

Most aquarium specimens grow to about 25–30 cm. Strong jaws and sharp teeth allow them to grasp and swallow relatively large prey items, so tankmates must be chosen accordingly.

Feeding

Snakeheads are carnivores that hunt fish, frogs, insects and other aquatic animals. In the aquarium they accept a wide range of meaty foods, including pieces of fish and shrimp, earthworms, krill, high‑quality frozen foods and sinking carnivore pellets.

As with other large predators, feeding warm‑blooded meat is not recommended. Offer varied but moderate portions to prevent obesity and maintain good water quality. Feeding after lights out often feels more natural for them.

Care and aquarium setup

A single African Snakehead requires an aquarium of at least 300 liters, with a larger footprint preferred. Use a tight‑fitting lid with no gaps — snakeheads are excellent escape artists and will use any opening to leave the tank.

Provide soft sand or fine gravel, plenty of hiding places made from driftwood, caves and dense planting, and keep lighting subdued. Filtration should be efficient but not create strong currents. Regular water changes and stable parameters are important, even though the species is more tolerant of low oxygen than most fish.

Behavior and compatibility

African Snakeheads are territorial and strongly predatory. They may tolerate robust tankmates of similar size in spacious tanks with many hiding places, but any fish small enough to fit in their mouth is at risk.

Keeping several snakeheads together is possible only in very large aquariums and usually works best with established pairs or groups raised from juveniles. Even then, aggression is possible, so close observation and backup plans are necessary.

Overview

The Hampala Barb (Hampala macrolepidota) is a large, fast‑swimming cyprinid from Southeast Asia. In the wild it is an important sport fish, and in the aquarium hobby it is kept by enthusiasts who enjoy active, shoaling predators in very large tanks.

Because of its size and energy level this species is not suitable for small aquariums or peaceful community setups. Young fish may look manageable, but they grow quickly and require substantial swimming space.

Habitat

Hampala Barbs inhabit rivers, streams, reservoirs and flooded forests in Thailand, Myanmar and neighbouring countries. They favour clear, well‑oxygenated waters with moderate current, often in the middle and upper layers of the water column.

Seasonal changes in water level influence their movements, with fish following schools of smaller prey and invertebrates along river channels and flooded areas.

Description

These barbs have a robust, torpedo‑shaped body adapted for fast swimming. The base colour is silvery to golden with dark vertical bars or blotches along the sides and a characteristic black band near the tail peduncle in many populations.

In nature they can reach 60–70 cm, although aquarium specimens are usually smaller. Nonetheless, even sub‑adult fish are large enough to view small tankmates as food.

Feeding

In the wild Hampala Barbs feed mainly on smaller fish and aquatic invertebrates. In captivity they readily accept a variety of foods: quality carnivore pellets, frozen fish and shrimp, krill, earthworms and other high‑protein items.

Avoid overfeeding fatty foods and provide a varied diet to support healthy growth and coloration. Because they are very active, they burn a lot of energy, but you still need to watch water quality closely.

Care and aquarium setup

A group of Hampala Barbs requires a very large aquarium, from 500 liters and ideally more. The tank should be long and wide to provide extended swimming runs. Use strong filtration and additional powerheads to create a moderate current, which helps mimic their natural environment.

Substrate can be sand or gravel, with rocks, driftwood and hardy plants along the back and sides. Maintain good oxygenation and regular water changes; this species is sensitive to high levels of nitrogenous waste.

Behavior and compatibility

Hampala Barbs are schooling fish and feel more secure in groups of at least five individuals. Lone specimens can become nervous and more aggressive. Within the group a loose hierarchy forms, but serious fights are rare in sufficiently large tanks.

Tankmates must be large, strong swimmers that can handle the constant movement and occasional chasing — for example other big cyprinids or large catfish. Small, slow or long‑finned fish are not suitable companions.

Overview

The name White Piranha is commonly used in the aquarium trade for large, silver‑coloured piranas related to the rhombeus group (Serrasalmus species). These fish are powerful, long‑lived predators that require spacious aquariums and careful handling.

Despite their fearsome reputation, properly kept piranhas usually behave shyly and prefer to hide when someone approaches the tank. Their main challenges are strong jaws, sharp teeth and the need for excellent water quality.

Habitat

In the wild these piranhas occur in South American river systems, including parts of the Amazon and Orinoco basins. They inhabit a variety of biotopes from slow blackwater tributaries to faster white‑water channels, most often staying near submerged roots, driftwood and overhanging vegetation.

Seasonal floods expand their feeding grounds into flooded forests and savannahs, where they follow schools of other fish and search for invertebrates and small vertebrates.

Description

White Piranhas have a deep, laterally compressed body with a blunt head, large eyes and a single row of sharp triangular teeth in each jaw. Colour is generally silver to grey with darker shading towards the back. Adults may develop darker patches or an overall smoky tone.

In captivity they can reach 25–30 cm or more, so even a single specimen is a sizeable fish. Their strong body and powerful tail allow rapid bursts of speed over short distances.

Feeding

In nature these fish feed on other fish, crustaceans and various animals that fall into the water. In the aquarium they accept a wide range of meaty foods: fish fillet, shrimp, mussels, earthworms and quality frozen diets formulated for large carnivores.

To avoid fatty degeneration of internal organs, do not offer mammal or poultry meat. Feed small portions several times per week rather than large meals every day, and remove leftovers promptly.

Care and aquarium setup

A single adult White Piranha should be housed in an aquarium of at least 400 liters, with larger volumes preferable. Provide efficient filtration, strong biological capacity and regular water changes to handle the heavy bioload of a large predator.

Use sand or fine gravel substrate, with roots, driftwood and sturdy plants to give the fish a sense of security. Dim lighting helps them feel calmer. A tight lid is advisable because startled piranhas can dash into the cover forcefully.

Behavior and compatibility

Piranhas can be kept singly or in species groups, but group dynamics are complex and often result in bullying and fin damage if the tank is too small. For most home aquarists keeping a single specimen is safer and easier.

They are not suitable for community aquariums. Any tankmate, even of similar size, may eventually be injured or killed, especially during feeding. Treat them as display fish in their own dedicated setup.

Overview

The Bowfin (Amia calva) is an ancient freshwater predator and the sole surviving member of the family Amiidae. All other related species are known only from fossils, making this fish a living representative of a lineage that dates back more than 100 million years. Found in eastern North America, the Bowfin inhabits slow-moving, heavily vegetated waters such as swamps, wetlands, oxbows, and shallow lakes. Because of its large adult size, long lifespan, and demanding care requirements, the Bowfin is rarely kept in home aquariums and is generally suited only to highly experienced aquarists.

Habitat

Bowfins are native to various regions across the United States and southeastern Canada. They prefer warm, shallow waters with abundant vegetation and soft substrates. Typical habitats include backwater channels, floodplains, quiet river margins, and swamp systems. These environments often experience seasonal changes in water quality and oxygen levels. The Bowfin’s physiology allows it to thrive in such unstable conditions, giving it a competitive advantage over many other fish.

Description

Bowfins have an elongated, cylindrical body with a broad head and a wide, powerful mouth lined with sharp teeth. Their long dorsal fin extends across more than half of the body length, giving the fish excellent maneuverability in dense vegetation. Coloration typically ranges from olive-brown to gray with darker mottling along the sides, providing camouflage in murky waters. Juveniles and adult males often display a distinct dark eyespot with a lighter outline near the base of the tail, a feature that may help distract predators.

Unique Physiology

One of the Bowfin’s most notable features is its ability to breathe atmospheric air. Its swim bladder functions similarly to a lung, enabling it to survive in waters with extremely low dissolved oxygen levels. This adaptation allows the Bowfin to inhabit stagnant or oxygen-depleted environments that many other fish species cannot tolerate. It also contributes to the species’ resilience during droughts or when isolated pools form as water levels drop.

Feeding

Bowfins are opportunistic predators. In the wild, they feed on fish, crustaceans, amphibians, aquatic insects, and other small animals. They typically hunt by lying in wait among vegetation and launching rapid ambush attacks.

In captivity, Bowfins readily accept a variety of meaty foods, including fish fillets, shrimp, mussels, earthworms, and other protein-rich items. They generally refuse dry prepared foods. Mammal or poultry meat should be avoided, as Bowfins cannot efficiently process the fats found in these tissues. Care should be taken not to overfeed, as excess organic waste can quickly deteriorate water quality in large aquariums.

Care and Aquarium Setup

Due to their size and natural behavior, Bowfins require a large aquarium — a minimum of 1000 liters. They are not particularly fast swimmers, but they need significant horizontal space and secure hiding areas. A natural biotope-style setup suits them best, featuring sand substrate, large driftwood, branches, stones, floating plants, and shaded zones.

Water movement should be minimal to replicate their natural environment. However, filtration must be strong, as large predatory fish generate substantial waste. Stable water parameters are essential: soft to medium hardness, a slightly acidic to neutral pH, and cool to moderate temperatures. Because of their longevity and environmental sensitivity, Bowfins are not recommended for beginners. Maintaining a Bowfin aquarium often requires specialized equipment and consistent care.

Behavior and Compatibility

Although Bowfins can appear calm, their predatory instincts remain strong. Small fish, shrimp, and most invertebrates will be eaten without exception. Tankmates must be large, robust species that can tolerate similar conditions and are unlikely to provoke aggression. Even then, compatibility is not guaranteed, as Bowfins may become territorial or defensive, particularly in confined environments.

They spend much of their time resting near structures, vegetation, or shaded areas, emerging to feed or investigate movement. Their behavior may change with age, feeding routine, and environmental conditions.

Breeding

Bowfins do not breed in home aquariums.
In the wild, males build nest-like depressions in shallow water, where females deposit eggs. After spawning, males aggressively guard the eggs and protect the fry until they reach several centimeters in length. This parental behavior increases offspring survival in natural environments.

Due to their large size and specific ecological requirements, successful captive breeding has not been documented in private aquaria.

Conclusion

The Bowfin is a remarkable and ancient species that offers a unique glimpse into the evolutionary history of ray-finned fishes. While it can be maintained in captivity, doing so responsibly requires a very large aquarium, powerful filtration, and a deep understanding of predatory fish care. For dedicated and experienced aquarists, the Bowfin can become a fascinating centerpiece — but it remains far beyond the scope of typical home aquarium keeping.

Overview

The reticulated stingray, Potamotrygon orbignyi, is a freshwater stingray species from the family Potamotrygonidae. In older literature it may appear under the synonym Potamotrygon reticulatus. This large freshwater stingray has become one of the most popular river stingrays kept by experienced aquarists. Its distinctive net-like pattern, active behavior and relatively peaceful temperament make it a fascinating but demanding aquarium inhabitant.

In nature reticulated stingrays are top predators within their ecosystem, feeding on small fish and invertebrates. In captivity they require very large tanks, powerful filtration and frequent feeding with high-quality meaty foods. Because of their size and sensitivity, this species is recommended only for aquarists already familiar with large fish and advanced husbandry.

Habitat

The species is native to South America. Its natural range covers wide areas of the Amazon and Orinoco river basins and also river systems in Suriname, Guyana and French Guiana. Reticulated stingrays inhabit a variety of biotopes, but are most often found in shallow, swampy sections of rivers with sandy or silty bottoms. Here the fish spend much of their time resting or partially buried in the substrate while waiting for prey.

Description

Like other river stingrays, the reticulated stingray has a classic disc-shaped body. The disc can reach about 35 cm in diameter, while the long, thin tail can extend the total length of the fish to more than twice the disc size. On the tail there is a sharp but fragile spine connected to venom glands, which the stingray uses primarily for self-defense. Proper handling and respect for the fish will prevent accidents, but aquarists should always be cautious when working in the tank.

The body pattern consists of a net-like or reticulated design made up of several shades of brown. This unique coloration gives the species its common name and helps to camouflage the ray against sandy and muddy riverbeds. Adult fish are impressive, truly a large freshwater stingray that becomes the center of attention in any aquarium.

Unique features and physiology

In comparison with some related Potamotrygon species, the reticulated stingray has a relatively small stomach in proportion to its body mass. This means it cannot take in large meals at once and instead needs to be fed frequently with small portions throughout the day. This physiological feature becomes especially important during transportation and acclimation, when feeding schedules are often disrupted. Young stingrays are particularly sensitive to irregular feeding and may arrive at the store already weakened.

Another critical aspect is the very long tail. During transport the tail can be strongly bent in cramped containers or even stay above the water surface for long periods if the bag or box is kept vertically. Such damage is the main cause of many health problems in this species. Because of these factors, choosing a healthy specimen at the time of purchase is essential for long-term success.

Behavior and compatibility

In the wild reticulated stingrays are active predators, so they pose a direct threat to most small fish and freshwater shrimp. Anything that can fit into their mouth is treated as potential food. At the same time, this freshwater stingray is not aggressive toward fish that are too large to be swallowed. With suitable tank mates it usually behaves calmly and focuses on searching the bottom for food.

Good companions include robust cichlids such as Geophagus species and Severum cichlids, as well as large Pimelodus catfish. In very spacious aquariums, reticulated stingrays can also be kept together with South American arowanas and large predatory fish similar in size and temperament. Delicate or slow-moving fish, as well as very small species, should be avoided.

Care and aquarium setup

For a single adult reticulated stingray, the recommended freshwater stingray tank size starts from 600 l. For this bottom-dwelling species the footprint of the tank is more important than its height; the ray needs a large open area to move and rest. The design of the aquarium can be simple, but the bottom must remain as free as possible from obstructions.

The substrate is a key element. Fine river sand or very small, smooth gravel is ideal, as the fish regularly buries itself partially in the ground. Sharp or coarse materials can damage the disc and underside. Decor may include a few large driftwood pieces, smooth rocks and heavy boulders, but they must be stable enough that the stingray cannot move or overturn them while digging.

Because the fish frequently disturbs the bottom, rooted plants are unlikely to survive; they are usually uprooted sooner or later. As an alternative, aquarists can use plants attached to driftwood or rocks, such as Anubias, many aquatic ferns and mosses. These add visual interest without occupying precious bottom space.

Filtration is one of the most important aspects of long-term care. As a carnivorous bottom feeder, this species produces a significant amount of organic waste. Efficient external filters, often more than one, are strongly recommended. Models with built-in heaters and aeration are especially convenient, as they reduce the number of devices inside the tank and free up swimming space. A good rule of thumb is that the filtration system should be able to move a volume of water equal to at least four times the capacity of the aquarium per hour. Water movement should be weak to moderate, avoiding strong currents near the bottom where the stingray rests.

Water quality depends not only on filtration but also on regular maintenance. Perform weekly water changes of about 50 % while siphoning uneaten food, feces and other organic waste from the substrate. Recommended parameters for this freshwater stingray species are a temperature of 24–26 °C, pH between 6.5 and 7.5 and soft water up to 10 dGH. The species does not require brackish conditions and should be kept in pure freshwater. Lighting is best kept subdued, which corresponds to its natural environment and helps the fish feel secure.

Feeding

In nature the reticulated stingray feeds mainly on small fish, freshwater shrimp and large invertebrates such as worms. In the aquarium its diet should be based on similar live or fresh foods. Suitable items include pieces of fish, shrimp, earthworms and other large worms. Juveniles readily accept bloodworms, tubifex, Artemia and similar small prey. Dry foods are generally not used for this species; it rarely accepts them and they do not satisfy its nutritional needs.

Because of the relatively small stomach capacity, food should be available frequently in small portions rather than in one or two large meals. Ideally, there should always be a small amount of food accessible on the bottom, without allowing excess to decompose. Special attention must be paid to young rays, which are much more vulnerable to starvation and can lose weight quickly if feeding is irregular. A well-fed fish will have a full, smooth body without visible protrusions at the base of the tail and without sunken areas under the eyes.

Choosing a healthy reticulated stingray

These rays are commonly offered for sale and may come either directly from South America or from breeding facilities in Europe and Asia. Regardless of origin, there is always a risk of buying a sick or emaciated specimen due to the difficulties of transportation and feeding. Before purchasing, try to observe the fish during feeding. Healthy individuals eagerly accept food and actively search for it on the bottom.

Inspect the animal carefully. There should be no visible kinks or injuries on the tail, as these often lead to infections. The area at the base of the tail should look full, not bony or sharply outlined. Under the eyes there should be no deep hollows. All these signs indicate exhaustion and poor condition, which can be hard to reverse even in excellent aquarium conditions. Choosing a strong, well-fed specimen at the beginning greatly increases the chances of success with this demanding large freshwater stingray.

Breeding

The reticulated stingray is a viviparous species. The young develop inside the female’s body and are born fully formed. Gestation lasts several months, and during a single season the female may produce only 1–8 pups. Observations suggest that in aquariums the gestation period can be somewhat shorter than in the wild, probably due to constant temperature and abundant food.

These rays are very selective when choosing mates. Simply placing a male and a female together rarely results in successful reproduction. In captivity, experienced keepers usually acquire a group of young rays and allow them to grow together, letting them form compatible pairs naturally. This process may take several years, which makes breeding unsuitable for the average hobbyist. For this reason, regular home aquariums rarely see deliberate breeding projects with this species, and most specimens available in shops are still collected from the wild or bred in specialized facilities.

Conclusion

The reticulated stingray is a striking and fascinating freshwater stingray species that can become a true centerpiece of a large aquarium. However, it is also a demanding fish that requires a very spacious tank, powerful filtration, stable soft water and frequent feeding with high-quality meaty foods. Careful selection of a healthy specimen and attention to water quality are essential for long-term success.

For aquarists ready to meet these requirements, this species offers the unique opportunity to observe the behavior of a river stingray in a well-planned home aquarium and to enjoy the beauty of its intricate net-like pattern and graceful movements along the sandy bottom.