Explore our growing database of freshwater fish species. Each profile includes detailed care requirements, compatibility data, and environmental needs to help you build the perfect aquarium.
Xiphophorus hellerii
A popular, highly active livebearer known for the male's elongated lower tail fin (the 'sword'). They are hardy but require larger tanks than other common livebearers (like Guppies or Platies) due to their size and immense swimming energy. They require hard, alkaline water and do best with a ratio of one male to multiple females to disperse harassment.
Vieja hartwegi
A robust and highly intelligent Central American cichlid known for its broad vertical tail bar, metallic sheen, and bold personality. Like many large Vieja species, they are heavy diggers, plant destroyers, and high waste producers. They can become fiercely aggressive, particularly towards similar-looking species or if their tank is too small.
Protomelas sp. "Steveni Taiwan"
A striking Lake Malawi Haplochromis (Hap) known for the breathtaking color transformation of mature males. Originating from the Taiwan Reef area in Africa (despite the misleading name), they are active swimmers that require hard, alkaline water, a sandy substrate for digging, and plenty of rockwork. They are primarily herbivorous in the wild and prone to 'Malawi Bloat' if fed too much heavy protein; a diet rich in spirulina is required.
Puntius tambraparniei
The Tambraparni Barb (now scientifically classified as Dawkinsia tambraparniei) is a medium-sized, highly active schooling fish native to the fast-flowing rivers of the Western Ghats in India. Known for their shimmering silver bodies adorned with striking dark blotches, they require a spacious aquarium with high water flow and high dissolved oxygen. While peaceful, their boisterous swimming can stress shy tank mates.
Glossolepis pseudoincisus
The Tami River Rainbowfish (frequently sold as the Millennium Rainbowfish) is a stunning, highly active shoaling species native to Papua, Indonesia. As they mature, males develop an intense, solid red coloration and a distinctively deep, arched back. They are fast swimmers that require plenty of open horizontal swimming space and do best in a mixed-sex school where males can display their best colors.
Tandanus tandanus
An Australian native, the Tandanus Catfish (or Eel-tailed Catfish) is an incredibly hardy, highly adaptable bottom-dweller. They possess a stout body that tapers into an eel-like tail. While generally peaceful towards large tank mates, they are highly predatory nocturnal scavengers and will eat any fish that fits in their cavernous mouths. Caution: They have sharp, mildly venomous serrated spines on their dorsal and pectoral fins.
Eretmodus cyanostictus
An intriguing, goby-like cichlid native to the shallow, highly oxygenated surge zones of Lake Tanganyika. They have a reduced swim bladder, causing them to 'hop' along the rocky bottom rather than swim freely. They require highly oxygenated water, strong flow, and a strict herbivorous diet (aufwuchs/algae) to avoid fatal intestinal bloat. They are highly intolerant of conspecifics unless kept as a bonded pair.
Potamotrygon laticeps
The term 'Teacup Stingray' is a highly deceptive trade name used for juvenile freshwater stingrays (often P. laticeps, P. motoro, or P. reticulata). They are not a miniature species. They are highly intelligent, predatory bottom-dwellers that require pristine water, massive aquariums, and fine sand to prevent lethal infections on their soft underbellies.
Telmatochromis brichardi
A small, fascinating cichlid endemic to the rocky coastlines of Lake Tanganyika. They are predominantly crevice and cave brooders that will also readily adopt empty snail shells in the aquarium. They form temporary pairs to breed, with males fiercely defending the territory while the female cares for the offspring. They require hard, highly alkaline water typical of the African Rift Lakes and a diet that incorporates algae.
Telmatochromis dhonti
A deeply territorial and highly aggressive substrate-spawning cichlid endemic to Lake Tanganyika. Known for their pugnacious behavior, they will fiercely dominate their territory and attack tank mates much larger than themselves. They require a rocky biotope with extensive cave networks and a sandy substrate. Sexually dimorphic in size.
Zoogoneticus tequila
The Tequila Splitfin is a critically endangered Goodeid livebearer endemic to a single spring system in Mexico. Famous for being saved from extinction by the aquarium hobby and successfully reintroduced to the wild. They are active, robust fish that require cooler water and alkaline conditions. They can be slightly nippy and are best kept in a species tank or with fast-moving, similarly sized tank mates.
Polypterus teugelsi
A rare, prehistoric-looking species native to the Cross River in Cameroon. It is uniquely colored with a reticulated black pattern on an olive background and a striking orange belly. Like all bichirs, it possesses a primitive pair of lungs and must breathe atmospheric air. It is nocturnal, carnivorous, and will consume any fish small enough to fit in its mouth. Ensure the tank has a tight-fitting lid, as they are notorious escape artists.
Herichthys cyanoguttatus
The Texas Cichlid is the only cichlid species native to the United States. Known for their striking pearlescent blue/green spots and extreme territorial behavior, they require large tanks and robust filtration. They are notorious for rearranging aquariums, digging massive pits, and destroying live plants.
Limnopilos naiyanetri
The Thai Micro Crab is a fully aquatic, extremely small freshwater crab native to a single river system (the Tha Chin river) in Thailand. They are exceptionally peaceful and lack standard defensive capabilities. Instead of hunting, they use tiny hairs on their claws to catch detritus and filter-feed biofilm. Due to their miniature size and incredibly shy nature, they must be kept with peaceful nano tank mates (like Neocaridina shrimp) or in a species-only setup to prevent predation.
Datnioides undecimradiatus
A large, striking predatory fish native to the Mekong basin, easily identified by its relatively narrow vertical stripes. It is highly sought after but listed as Vulnerable (VU) on the IUCN Red List due to overfishing and habitat degradation. They are stealthy ambush predators with large, highly protrusible mouths capable of swallowing remarkably large prey. They prefer dimly lit tanks with ample driftwood for cover.
Acarichthys heckelii
A stunning, generally peaceful South American cichlid closely related to the 'Earth-eaters' (Geophagus). They are famous for the long, trailing red filaments extending from their dorsal fins. They continuously sift substrate for food, making fine sand an absolute requirement for their gills and natural behaviors. While relatively peaceful in a community of similarly sized fish, they become fiercely territorial during breeding.
Iriatherina werneri
A delicate and exquisitely shaped nano rainbowfish native to New Guinea and Northern Australia. They are famous for the males' long, filamentous fins and butterfly-like display behavior. Due to their incredibly small throats, they require micro-foods. They are shoaling fish that are easily intimidated by boisterous tank mates.
Trichopodus trichopterus
A robust, semi-aggressive labyrinth fish available in many color morphs (Blue, Gold, Opaline). Biologically, they are all the same species. Unlike the peaceful Pearl Gourami, Three Spots are boisterous and can be bullies. They are excellent for 'semi-aggressive' community tanks (e.g., with Tiger Barbs, large Tetras) but may harass shy or long-finned fish.
Exochochromis anagenys
A striking, large predatory haplochromine cichlid endemic to Lake Malawi. Known for its torpedo-shaped body (fusiform), it is an open-water hunter that preys on smaller fish like mbuna. While highly predatory and requiring a massive tank, they are relatively mild-mannered toward tankmates too large to be swallowed. Conspecific males, however, are violently intolerant of one another.
Apistogramma trifasciata
A stunning dwarf cichlid native to the Guaporé and Paraguay river basins in South America. They are renowned for their striking metallic blue sheen and the male's spectacular sail-like dorsal fin. As peaceful micropredators, they are excellent for planted community tanks, but require soft, acidic water, stable parameters, and a fine sand substrate to sift through.
Puntigrus tetrazona
A highly active, schooling cyprinid famous for its striking black stripes and infamous reputation as a fin-nipper. They are boisterous and must be kept in larger groups (6+) to keep their pecking order internal. They should never be housed with slow-moving or long-finned tankmates like Bettas, Guppies, or Angelfish.
Devario maetaengensis
The Tiger Danio is a striking, fast-swimming schooling fish endemic to the clear, fast-flowing headwaters of northern Thailand. Known for their bold vertical barring and highly energetic nature, they require specialized 'hillstream' setups with pristine, highly oxygenated water and strong flow. Due to their intense activity levels, they should not be kept with slow-moving or shy tank mates.
Syncrossus hymenophysa
A large, highly active, and notably aggressive loach recognized by its striking vertical stripes. Unlike most peaceful botiid loaches, the Tiger Loach is highly territorial and a notorious fin-nipper. They are social but possess a strict, often violent hierarchy; they must be kept in groups of 5+ to disperse aggression. Excellent at eradicating snails, but require fast-moving, robust tank mates (e.g., large barbs).
Esox masquinongy x lucius
A sterile hybrid of the Muskellunge and Northern Pike. It is a massive, voracious apex predator that grows incredibly fast. Due to its extreme size, explosive ambush hunting style, and strictly piscivorous diet, it is only suitable for the largest custom aquariums or indoor ponds.
