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.
Aulonocara sp. 'Rubescens'
A stunning, line-bred Peacock cichlid originating from Lake Malawi. Known for their vibrant red/orange coloration. As part of the Aulonocara genus, they possess specialized sensory pores on their lower jaw used to detect micro-prey hidden in the substrate, making fine sand an absolute requirement. They are moderately aggressive but generally more peaceful than Mbuna cichlids.
Hyphessobrycon sweglesi
A peaceful, deep-bodied tetra known for its vibrant red coloration and distinct black shoulder spot. Native to the Orinoco River basin, they prefer slightly cooler water than most tropical tetras and thrive in well-planted, dimly lit aquariums. Males will frequently engage in harmless, display-oriented sparring by flaring their fins.
Glossolepis incisus
Native to Lake Sentani in Indonesia, this species is famous for the brilliant salmon-red coloration of mature males. They are large, active schooling fish that develop a distinct high-arched back as they age. Females are vastly different in appearance (olive-gold). They require hard, alkaline water and plenty of swimming space.
Geophagus surinamensis
A large, relatively peaceful South American cichlid famous for its 'earth-eating' behavior. They constantly sift fine sand through their gills to forage for benthic invertebrates. A soft sand substrate is absolutely mandatory for their long-term health to prevent gill damage and stress. While gregarious and best kept in groups, they establish a strict pecking order.
Procambarus clarkii
A highly active, hardy, and notoriously aggressive freshwater crustacean. Procambarus clarkii are opportunistic omnivores and apex bottom-dwellers in most aquariums. They are incredibly destructive to live plants, will rearrange substrate, and eagerly hunt bottom-sleeping fish, snails, and shrimp. They require a secure, tight-fitting lid as they are expert escape artists.
Acestrorhynchus falcatus
A fast-moving, torpedo-shaped predator native to the Amazon and Orinoco basins. Despite the name, it is a characin, not a true marine barracuda. It is strictly piscivorous (eats other fish) and requires a large, long aquarium with high flow and a tight-fitting lid due to its tendency to jump when startled. Highly predatory but can be skittish if kept with aggressive or overly boisterous tankmates.
Epalzeorhynchos bicolor
A striking and highly active bottom-dwelling cyprinid known for its jet-black body and vibrant red tail. While beautiful, they are notoriously territorial, especially toward their own kind, similar-looking species (like Rainbow Sharks), and sometimes other bottom-dwellers. They must be kept as the only 'shark' in the tank and require a large footprint with plenty of caves and broken sightlines.
Carinotetraodon irrubesco
A small, true freshwater pufferfish native to the river basins of Indonesia. Known for their striking red eyes and highly inquisitive nature. While considered one of the more 'peaceful' Carinotetraodon species, they are still notorious fin-nippers and specialized predators of snails and dwarf shrimp. They require a heavily planted tank to break lines of sight.
Mesoheros festae
A massive, apex-predator South American cichlid. Known as the 'Red Terror' due to its absolute intolerance of tank mates and extreme territorial aggression. They are powerful 'glass-bangers' that will uproot plants, rearrange decor, and kill fish of similar or even larger size. Best kept completely alone or as a strictly bonded pair in a massive aquarium.
Metriaclima greshakei
An attractive and robust Mbuna cichlid native to the rocky shores of Lake Malawi. They are highly sexually dimorphic. Like most Mbuna, they require hard, alkaline water, intricate rockwork to establish territories, and a specialized herbivore-leaning diet to prevent digestive issues (Malawi bloat).
Caridina serrata
The Red Tupfel Shrimp is a selectively bred color morph of the wild Tupfel (Spotted) Shrimp (Caridina serrata). They feature a translucent body with striking red spots. They are closely related to Tiger and Bee shrimp but are generally considered slightly more hardy and forgiving of water parameters. They thrive in established nano setups with plenty of biofilm to graze on.
Metriaclima estherae
A highly popular and vibrant Mbuna cichlid from Lake Malawi. The 'Cherry Red' or Orange morph is a favorite for African Cichlid setups. They are rock-dwelling (Mbuna), highly territorial, and require a diet rich in vegetable matter (algae/spirulina) to avoid Malawi Bloat. Best kept in a harem ratio of 1 male to 3+ females.
Pygocentrus nattereri
An infamous South American predator known for its razor-sharp teeth and schooling behavior. Despite their fearsome reputation, they are naturally skittish and easily spooked in aquariums, requiring a large shoal (4-6+) and dim lighting (often achieved via floating plants) to feel secure. They are incredibly messy eaters that produce extreme bioloads, necessitating massive filtration systems and frequent water changes.
Melanotaenia rubripinnis
A stunning, active schooling fish native to the Wapoga River system of West Papua. They thrive in planted aquariums with moderate flow, mimicking their natural habitat of streams and shaded pools. Like most rainbowfish, they are peaceful but extremely active and require plenty of lateral swimming room.
Phractocephalus hemioliopterus
A massive, fast-growing predatory catfish from the Amazon basin. Famous for its voracious appetite, bulldozer-like behavior, and distinct red caudal fin. Due to its enormous adult size (often exceeding 4 feet), it is strictly a 'monster fish' that requires a heated indoor pond or a colossal custom aquarium. It is highly predatory and will swallow absolutely any tank mate that can fit into its cavernous mouth.
Lepomis auritus
A colorful, North American native freshwater fish known for its bright orange-red belly and an elongated, solid black opercular flap ('ear'). As a temperate species, they thrive in unheated aquariums. They are aggressive, territorial predators that will dig nests in the substrate and consume any tank mate small enough to fit in their mouths.
Lepomis microlophus
A robust North American native fish commonly known as the 'Shellcracker' due to its specialized pharyngeal teeth used to crush snails and mollusks. They are a temperate (coldwater) species that makes an excellent subject for a large native unheated aquarium. They are semi-aggressive, territorial, and will consume any tank mate small enough to fit in their mouths.
Vieja melanura
A massive, deep-bodied Central American cichlid famous for its vibrant pastel colors and prominent red head. In the wild, they are primarily herbivorous, but in captivity, they are opportunistic omnivores. They are aggressive, territorial, and possess immense jaw strength, making them capable of destroying most aquatic plants and rearranging tank decor at will.
Heros sp. Rotkeil
A striking, deep-bodied South American cichlid known for the intense red/orange coloration on its head and shoulders. While generally considered a 'gentle giant' compared to other large cichlids, it is highly territorial during breeding. They are notorious herbivores that will enthusiastically consume most live aquatic plants.
Rasbora pauciperforata
A slender, elegant schooling fish native to the blackwater peat swamps of Southeast Asia. Distinguished by a brilliant, glowing neon-red stripe running from its mouth to its tail. They are true blackwater fish, requiring soft, acidic water and plenty of tannins from leaf litter or driftwood to thrive and show their best colors. Peaceful but can be skittish if not kept in appropriately large schools with overhead cover.
Xenotoca eiseni
A robust and highly active livebearer endemic to Mexico (Goodeidae family). Unlike standard livebearers, females nourish their young via umbilical-like structures (trophotaenia) rather than yolks. They are infamous in the hobby as aggressive fin-nippers and should absolutely not be kept with slow-moving or long-finned fish (like Bettas, Angelfish, or Corydoras). They require hard, alkaline water and cooler temperatures.
Erpetoichthys calabaricus
An ancient, eel-like species from West Africa closely related to Bichirs. They are famous for their snake-like appearance and gentle nature. Unlike Bichirs, Ropefish are social and prefer to be kept in groups. They are nocturnal hunters using smell to find food. WARNING: They are legendary escape artists; a tight-fitting lid without even the smallest gap is 100% mandatory.
Julidochromis regani
A slender, rock-dwelling cichlid endemic to the shallow, rocky shorelines of Lake Tanganyika. Known for their distinct horizontal stripes and torpedo-like bodies, they are highly territorial over rock crevices. They form strong, monogamous pair bonds but are notoriously aggressive toward conspecifics (other Julies) and benthic competitors.
Sewellia lineolata
A fascinating, highly specialized loach adapted to fast-flowing, oxygen-rich rapids. They have a flattened, ray-like body allowing them to cling to smooth rocks where they graze on algae and biofilm (aufwuchs). They strictly require strong water flow, high dissolved oxygen, and cooler temperatures. Males frequently engage in visually striking but harmless territorial 'battles' over prime feeding rocks.
