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.
Melanotaenia misoolensis
An active, schooling species endemic to the limestone karst streams of Misool Island in West Papua, Indonesia. They are found in moderately fast, clear waters flowing through primary rainforests. Like many rainbowfish, they are slow to mature but develop stunning colors and deep bodies as adults. They require hard, alkaline water and ample horizontal swimming space.
Polypterus mokelembembe
A fascinating 'living fossil' from the Congo River Basin, named after a mythological African dinosaur. While considered one of the smaller bichir species, it still reaches up to 36cm (14 inches). Like all bichirs, they possess a modified swim bladder acting as a lung, requiring access to atmospheric air. They are nocturnal ambush predators with heavily armored, eel-like bodies.
Poecilia sphenops
Mollies are active, hardy livebearers native to the Americas. They are famous for their ability to adapt to fresh, brackish, and even full marine water. They are voracious eaters (including algae) and produce a high bioload for their size. Note: 'Molly' covers several species; the Short-finned (*P. sphenops*) and the much larger Sailfin (*P. latipinna* and *P. velifera*).
Monodactylus sebae
A striking, deeply compressed (diamond-shaped) schooling fish native to the estuaries and mangroves of West Africa. While juveniles are frequently found in freshwater or light brackish water, adults strictly require high brackish to full marine conditions to survive long-term. They are hyperactive, grow extremely tall, and require massive, open aquariums to accommodate their schooling nature.
Hoplias aimara
An apex predator native to the fast-flowing rivers of South America. The Aimara is notorious for its incredible jaw strength, massive teeth, and unmatched aggression. It is arguably the most aggressive freshwater aquarium fish and will violently attack tankmates, equipment, and even the keeper's hands. It must be housed completely alone in a highly secure, massive aquarium with heavily weighted or lockable lids to prevent them from jumping or shattering the glass during feeding strikes.
Trichogaster microlepis
A gracefully sloping, large labyrinth fish characterized by its beautiful, iridescent silvery sheen and exceptionally long, thread-like ventral fins (feelers). While peaceful and somewhat timid, they are notorious for nibbling on soft-leaved and fine aquarium plants. They require access to the surface to breathe atmospheric air.
Gambusia affinis
An extremely hardy livebearer historically introduced worldwide for mosquito control. In the aquarium, they are notorious fin-nippers and highly aggressive towards other small fish. They are best kept in species-only setups or indoor/outdoor ponds. Males are significantly smaller than females.
Potamotrygon motoro
A spectacular but highly demanding freshwater stingray native to South America, instantly recognizable by its orange-spot 'peacock' pattern. They are massive, heavy-polluting predators that require huge aquariums with pristine water quality. A soft sand substrate is absolutely mandatory to prevent severe bacterial infections on their delicate underbellies. Note: They possess a venomous tail stinger.
Paracanthocobitis botia
A highly active, rheophilic (current-loving) loach native to fast-flowing streams in South Asia. Known for their intricate mottled patterns and 'zipper-like' lateral line, they are boisterous and establish clear social hierarchies. They must be kept in groups to prevent bullying and require well-oxygenated water with a smooth substrate to protect their delicate barbels.
Melanotaenia monticola
A striking and active schooling fish endemic to the high-altitude, fast-flowing mountain streams of Papua New Guinea. Because of their natural habitat, they are unique among Rainbowfish for requiring significantly cooler, highly oxygenated water. They feature a blue-grey to greenish body with a distinct black mid-lateral stripe and coppery golden scale margins.
Oreochromis mossambicus
A massive, incredibly hardy, and euryhaline cichlid native to southeastern Africa. Known for its extreme adaptability, it can thrive in completely fresh to fully marine water. In the aquarium, it is a heavy-bodied, fast-growing fish that will ruthlessly dig, uproot plants, and rearrange the substrate. Due to extreme waste production and territorial aggression, it requires a very large tank with heavy filtration.
Metriaclima sp. "Msobo"
A highly prized Mbuna from Lake Malawi famous for extreme sexual dimorphism. They are rock-dwelling aufwuchs grazers that require hard, alkaline water. Like most Mbuna, they are highly territorial and aggressive, requiring overstocking and careful male-to-female ratios (harems) to disperse aggression. A minimum 4-foot tank with copious rockwork is mandatory.
Melanotaenia mubiensis
A rare, energetic, and colorful schooling fish native to the clear, limestone-filtered streams of the Kikori River system in Papua New Guinea. As they mature, males develop striking colors and deep bodies. Like most rainbowfish, they are highly active, requiring long aquariums with moderate flow and moderately hard, alkaline water to thrive.
Melanotaenia fluviatilis
A robust and active schooling fish native to the cooler waters of the Murray-Darling basin in Australia. Unlike many tropical rainbowfish, it thrives in subtropical or unheated aquariums at normal room temperatures. They are peaceful but extremely fast swimmers, requiring long tanks with plenty of open swimming space.
Pomacea bridgesii
A large, popular, and active freshwater snail. Unlike other apple snails, they generally do not eat live, healthy plants, preferring algae, detritus, and sinking foods. They require calcium-rich, alkaline water to prevent shell erosion. Females will frequently leave the water to lay distinct pink egg clutches above the waterline.
Microdevario nana
A true micro-fish endemic to Myanmar, the Nana Rasbora rarely exceeds 1.5cm (0.6 inches). They exhibit a translucent yellowish body with a subtle iridescent blue lateral stripe and a distinct black blotch on the dorsal fin. Due to their minute size, they are completely peaceful, highly shrimp-safe, and must be kept in schools of at least 6-8 in densely planted, mature aquariums. Providing leaf litter and dim lighting will help them feel secure.
Xenentodon cancila
A fascinating, highly predatory surface-dwelling fish with a long, beak-like mouth filled with sharp teeth. Despite the common name, it is a needlefish, not a true gar. They are notoriously skittish and prone to fatal jumping or injuring their delicate snouts on tank walls if startled. They strictly require a tight-fitting lid and a very long tank with open swimming space at the surface.
Neolamprologus fasciatus
An ambush predator endemic to Lake Tanganyika. It is a specialized shrimp-eater and piscivore, famous for a unique hunting technique where it remains completely motionless before striking its prey. Unlike many Tanganyikan cichlids, they are not strictly rock-bound and often utilize empty snail shells on sandy bottoms for spawning.
Neolamprologus pulcher
An elegant but fiercely territorial African cichlid native to Lake Tanganyika. Known in the hobby as the Daffodil Cichlid, they are famous for their unique 'stepped' colony breeding behavior, where multiple generations of older siblings help raise the newest batches of fry.
Neolamprologus similis
A fascinating dwarf cichlid endemic to Lake Tanganyika. Known as a 'shell dweller' (or shellie), they live, breed, and seek refuge in empty snail shells (like Escargot or Neothauma shells). They are highly social, forming complex multi-generational colonies. They require hard, alkaline water, a sandy substrate for excavation, and at least 2-3 shells per fish.
Neolamprologus tretocephalus
An endemic cichlid from Lake Tanganyika known for its striking resemblance to the much larger Frontosa cichlid. Despite its moderate size, the 'Tret' is highly aggressive and territorial. In the wild, they are specialized molluscivores (snail eaters) with powerful jaws. They require hard, alkaline water and rockwork caves.
Paracyprichromis nigripinnis
A remarkably peaceful, schooling African cichlid native to the deep, rocky habitats of Lake Tanganyika. They are famous for their unique behavior of swimming closely aligned to vertical rock faces or even hanging upside down in cave overhangs. They are maternal mouthbrooders that absolutely require groups, hard/alkaline water, and plenty of vertical rockwork.
Stiphodon atropurpureus
A stunning, specialized freshwater goby native to fast-flowing hill streams in Asia. Males display brilliant neon blue metallic coloration, while females are striped. They are specialized biofilm grazers ('Aufwuchs' eaters) and require mature tanks with established algae/biofilm stones. They are obligate stream dwellers requiring high oxygen and strong flow.
Microdevario kubotai
A brilliant neon-green nano schooling fish native to the slow-to-moderate rivers of Thailand and Myanmar. Despite their tiny size, they are highly active, darting swimmers that require plenty of horizontal swimming space and well-oxygenated water. They are strictly shoaling fish and must be kept in groups to feel secure and display their best colors.
