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.
Ctenolucius hujeta
The Freshwater Barracuda, or Hujeta Pike Characin, is an elongated, torpedo-shaped ambush predator. It primarily inhabits the upper water levels. Though peaceful with fish too large to swallow, it is a highly efficient piscivore and will readily consume smaller tank mates like Tetras or Guppies. Known to be skittish and prone to fatal jumping, a tight-fitting lid is strictly required.
Trinectes maculatus
Despite the trade name 'Freshwater Flounder', Trinectes maculatus is actually a euryhaline flatfish native to coastal estuaries in North America. While juveniles migrate into fresh water, adults require at least low-end brackish water (SG 1.005+) for long-term health and a normal lifespan. They are highly specialized, nocturnal ambush predators that spend most of their time buried in fine sand. Keeping them on sharp gravel will severely damage their undersides and lead to infection.
Caridina cf. spongicola
An expert-level, tiny freshwater shrimp endemic to Lake Towuti in Sulawesi. Known for its striking red and white bands and shy nature. In the wild, they live symbiotically with a specific freshwater sponge, though in aquariums they can be sustained on mature biofilm. They require extremely stable, warm, alkaline water parameters and should only be kept by advanced aquarists.
Wallago attu
An apex predator native to South and Southeast Asia, infamous for its immense size, huge mouth, and voracious predatory nature. It will consume any tank mate that fits into its capacious mouth and is known to bite aggressively when handled. This species is utterly unsuitable for standard home aquariums and requires an enormous custom pond or public aquarium setup.
Brachirus selheimi
A rare and captivating bottom-dwelling flatfish native to Australia and New Guinea. As an ambush predator, it spends most of its time completely buried in fine sand, waiting to strike at small fish or crustaceans. It absolutely requires a soft sand substrate to thrive and prevent severe abrasions to its delicate underside.
Thalassophryne amazonica
A highly cryptic, sedentary ambush predator native to the Amazon basin. WARNING: This species possesses hollow, venomous spines on its dorsal fin and gill covers; handle with extreme caution. They spend most of their time buried in the substrate and are capable of swallowing tankmates nearly their own size. While inactive, they require excellent filtration due to the high waste produced by a predatory diet.
Chaca chaca
An incredibly bizarre ambush predator native to South Asia. With a massive, flat head and cryptic coloration, they perfectly mimic a dead leaf or piece of wood. They are entirely sedentary, moving only to gulp down prey that wanders too close to their cavernous mouths. Because they can easily consume fish up to half their own length, tank mates must be chosen with extreme caution.
Cyphotilapia frontosa
A majestic and iconic deep-water cichlid from Lake Tanganyika, famous for its striking black and white bands and the prominent nuchal hump on its head. Despite their massive size, they are gentle giants compared to other African cichlids. However, they are highly effective piscivores and will easily consume smaller fish. They are best kept in a 'harem' colony of one male to multiple females.
Labeotropheus fuelleborni
A robust, highly active Mbuna cichlid from Lake Malawi, easily recognized by its distinct fleshy, overhanging snout used for scraping algae (aufwuchs) from rocks. They are fiercely territorial and require a strictly herbivorous diet to avoid fatal digestive issues like Malawi Bloat.
Nandus nandus
An ambush predator native to South Asia, the Gangetic Leaf Fish relies on its mottled camouflage to mimic dead leaves. It has a remarkably large, protrusible mouth and is strictly piscivorous, swallowing smaller fish whole. It requires a dimly lit tank with low flow, heavy planting, and leaf litter to feel secure. Due to its highly predatory nature, it must only be housed with fish too large to be eaten.
Fundulopanchax gardneri
A stunning, semi-annual killifish native to Nigeria and Cameroon. Known for being relatively hardy and an excellent 'beginner' killifish. They are notorious jumpers and require a tightly fitting lid. While they can be kept in community tanks with similarly sized, fast-moving fish, males can be boisterous and territorial.
Hemigrammus pulcher
A beautiful, deep-bodied tetra native to the slow-moving tributaries of the upper Amazon basin. They are distinguished by a striking black wedge-shaped patch near their tail, framed by a shimmering garnet or coppery hue. They are peaceful schooling fish that look their best in mature, dimly lit blackwater aquariums.
Geophagus sp. 'Orange Head'
A stunning and relatively peaceful South American 'eartheater' native to the Rio Tapajós. They are famous for the vibrant orange/red coloration on the heads of mature adults and their fascinating feeding behavior. They are gregarious and must be kept in groups. Fine sand substrate is absolutely mandatory, as they constantly sift it through their gills to forage.
Mikrogeophagus ramirezi
A strikingly colorful dwarf cichlid native to the Orinoco River basin. Famous for its vibrant blue spangles and peaceful demeanor compared to larger cichlids. They are strictly thermophilic (require high temperatures of 27-30°C / 81-86°F) and thrive in soft, acidic water. As 'earth-eaters' (Mikrogeophagus), they sift sand for food and form monogamous pairs.
Pseudomugil gertrudae
A stunning, highly active nano fish native to Australia and New Guinea. Known for their striking blue eyes and the males' spectacular, heavily spotted fins which they flare during dominance displays. They are peaceful but require being kept in shoals to thrive and exhibit natural behaviors.
Palaemonetes paludosus
A completely transparent freshwater shrimp native to the southeastern United States. While frequently sold as inexpensive feeder animals, they make fascinating, active scavengers for nano and peaceful community tanks. They tirelessly consume uneaten food and detritus but have a relatively short lifespan of 1 to 2 years.
Devario aequipinnatus
The Giant Danio is a robust, incredibly active schooling fish native to fast-flowing streams in South Asia. Known for their striking blue and gold horizontal stripes, they are constantly in motion and require long tanks with strong water flow. Due to their boisterous nature, they make excellent 'dither fish' for mild-mannered cichlids but should not be kept with slow, shy, or long-finned species as they will easily outcompete them for food.
Osphronemus goramy
The Giant Gourami is a massive, highly intelligent anabantoid that behaves more like a wet pet than a typical community fish. They grow extremely large and have voracious appetites, often completely consuming any live plants in their tank. Due to their immense adult size and extreme bioload, they require massive aquariums and robust filtration.
Proloricaria prolixa
Proloricaria prolixa (formerly Loricaria prolixa), commonly known as the Giant Whiptail, is a large, heavily armored catfish endemic to the upper Paraná River basin in Brazil. They are specialized benthic grazers that require cooler subtropical temperatures, strong water flow, and highly oxygenated water. Despite reaching impressive sizes (up to 35cm/14in), they are generally peaceful and feed primarily on periphyton and biofilm.
Prionobrama filigera
A highly active, schooling characin characterized by its translucent body and striking blood-red anal fin. They are peaceful but exceptionally fast-moving, requiring plenty of open horizontal swimming space in the upper levels of the aquarium. They are known to be skilled jumpers, making a tight-fitting lid mandatory.
Kryptopterus vitreolus
A highly unique, completely transparent catfish from Thailand. Unlike most catfish, they are mid-water swimmers that require being kept in schools to feel secure. They are incredibly peaceful and easily outcompeted for food. They require stable water parameters and dim lighting or shaded areas provided by floating plants.
Danio choprae
A strikingly colorful and hyperactive nano fish native to the Irrawaddy River drainage in Myanmar. Named for its glowing orange/red horizontal bands and vertical barring. Despite their small size, they are incredibly fast, dynamic swimmers that require a long aquarium with ample swimming space. They must be kept in large schools and are notorious jumpers, so a tight-fitting lid is mandatory.
Hemigrammus erythrozonus
A peaceful, schooling nano fish native to the Essequibo River basin in South America. They are famous for their translucent bodies and the striking iridescent neon-orange stripe running from snout to tail. They thrive in mature, planted aquariums with slightly soft, acidic water and subdued lighting.
Parotocinclus jumbo
A unique dwarf Loricariid native to fast-flowing streams in northeastern Brazil. Unlike typical plecos, the Pitbull Pleco stays very small and requires the company of its own kind to feel secure. They are excellent algae grazers and a fantastic alternative to Otocinclus. Uniquely, when startled or resting, they will dive directly into the substrate and bury themselves, making a soft sand bed absolutely essential for their wellbeing.
