Here are some of the most popular freshwater fish species that are commonly kept in aquariums, each with unique characteristics and care requirements.
A common rule of thumb for how many freshwater fish you can keep in an aquarium is to allow about 1 inch of fish per gallon of water; however, this can vary depending on the specific fish species, their adult size, activity level, and bioload, with heavily planted or densely stocked tanks often needing more filtration and swimming room.
Overview One of the most popular and recognizable aquarium fish. Lives in acidic forest streams, often stained with tannins (blackwater), with leaf litter and roots. Has a bright blue lateral stripe. The red pigment does not extend forward past the pectoral-fin base....
Overview The African Jewelfish (Hemichromis bimaculatus), also sold as the jewel cichlid, is a colorful West African cichlid that turns brilliant red when breeding. Found in small streams and canals along Africa's west coast, from southern Guinea to central Liberia....
Overview The Betta (Betta splendens), or Siamese fighting fish, is one of the best-known aquarium fish. Native to central Thailand, where it lives in rice paddies, swamps, ditches and slow streams. Wild fish reach about 2.8 in (7 cm) standard length. Long-finned...
Overview The Black Angelfish is a solid black color form of the freshwater angelfish (Pterophyllum scalare). Wild angelfish come from the Amazon basin in Brazil, Peru and Colombia, and from the Guianas. Grows to about 6 in (15 cm) long and taller with the fins, so it...
Overview The Black Molly is a black, captive-bred form of the common molly (Poecilia sphenops). Wild mollies range from Mexico south to Colombia and Venezuela. Grows to about 3.1 in (8 cm). Many black mollies in stores are hybrids with other molly species. Feeding...
Overview The Black Phantom Tetra (Hyphessobrycon megalopterus) is a peaceful, smoky-gray tetra with a black shoulder spot and large fins. Native to the upper Rio Madeira basin in Bolivia and western Brazil, and the Rio Paraguay basin. Grows to about 1.4 in (3.6 cm)...
Overview The Black Skirt Tetra (Gymnocorymbus ternetzi), also known as the Black Widow Tetra, is a hardy, deep-bodied tetra with black vertical bars and a dark rear half. Native to slow creeks and streams with overhanging plants in the Paraguay and Guaporé basins of...
Overview The Bloodfin Tetra (Aphyocharax anisitsi) is a silvery tetra with bright red fins. Native to the Paraná River basin in Brazil, Paraguay and Argentina. Grows to about 2.2 in (5.5 cm) standard length. A hardy beginner fish that adapts to a wide range of...
Overview The Bristlenose Pleco (Ancistrus cf. cirrhosus) is the familiar bristlenose catfish sold in most stores. Males grow fleshy bristles on the snout. Grows to about 5 in (12.5 cm) standard length, much smaller than the common pleco. Mass-bred commercially. Its...
Overview The Bolivian Ram (Mikrogeophagus altispinosus) is a peaceful dwarf cichlid. It is also sold as the Bolivian butterfly cichlid. Native to the upper Rio Madeira basin in Bolivia and Brazil. Grows to about 3.1 in (8 cm) standard length. Usually a better choice...
Overview The Cardinal Tetra (Paracheirodon axelrodi) has a neon-blue stripe above a red lower body that runs the full length of the body. Native to forest streams in the Rio Negro and upper Orinoco basins of Brazil, Colombia and Venezuela. Grows to about 1.4 in (3.5...
Overview The Clown Loach (Chromobotia macracanthus) is a bright orange loach with black bands. It is very popular, but often bought without knowing how big it gets. Native to rivers of Borneo and Sumatra in Indonesia. Can reach about 16 in (40 cm), though it grows...
Overview The Duboisi Cichlid (Tropheus duboisi), or white-spotted cichlid, is a Lake Tanganyika cichlid. Juveniles are black with white spots and adults develop a pale band. Lives in rocky areas, in deeper water than other Tropheus. Grows to about 5 in (12 cm)...
Overview The Dwarf Gourami (Trichogaster lalius) is a colorful labyrinth fish. Males have red and blue bars. Native to Pakistan, northern India and Bangladesh, in slow, heavily planted ponds, swamps, ditches and canals. Grows to about 3.5 in (8.8 cm) standard length....
Overview The Convict Cichlid (Amatitlania nigrofasciata) is a hardy Central American cichlid with bold black bars. It is one of the most familiar cichlids in the hobby. Native to Guatemala, Honduras, El Salvador, Nicaragua, Costa Rica and Panama. Grows to about 6 in...
Overview The Discus (Symphysodon aequifasciatus and related Symphysodon species) is a disc-shaped Amazon cichlid prized for its color. Wild fish live in slow tributaries and forest pools along the Rio Solimões and Amazon. Grows to about 6 in (15 cm) long and nearly as...
Overview The Colombian Tetra (Hyphessobrycon columbianus) is a robust tetra with a blue-silver body and red fins. It is also sold as the blue-red or Colombian red fin tetra. Known only from the Río Acandí area in northern Colombia, near the Panama border. Grows to...
Overview "Common Pleco" is a trade name for several large suckermouth catfish, most often the Amazon sailfin catfish (Pterygoplichthys pardalis). Store fish may be a related species or Hypostomus plecostomus. P. pardalis is native to the Amazon basin in Brazil and...
Overview The Cockatoo Dwarf Cichlid (Apistogramma cacatuoides) is a hardy South American dwarf cichlid named for the male's tall, crest-like dorsal fin. Widespread in the upper Amazon basin, in slow tributaries, backwaters and creeks with leaf litter. Males reach...
Overview The Green Swordtail (Xiphophorus hellerii) is the wild-type form of the familiar swordtail. Males grow a long "sword" on the lower tail fin. Native to southeastern Mexico, Guatemala, Belize and Honduras. Grows to about 6 in (14 cm) standard length. The sword...
Overview The Glowlight Tetra (Hemigrammus erythrozonus) is a small, peaceful tetra with a glowing orange-red stripe. Known only from the Rio Essequibo in Guyana. Grows to about 1.6 in (4 cm) standard length. All fish sold are commercially farmed. An albino form is...
Overview The Frontosa Cichlid (Cyphotilapia frontosa) is a large, blue-and-white barred Lake Tanganyika cichlid with a prominent hump on the forehead. Native to the northern part of Lake Tanganyika. Grows to about 10 in (25.5 cm) standard length. Trade fish are often...
Overview The German Blue Ram (Mikrogeophagus ramirezi), also called Ramirez's dwarf cichlid or butterfly cichlid, is a small, jewel-like dwarf cichlid. Native to the llanos savanna wetlands of the Orinoco basin in Venezuela and Colombia. Grows to about 1.6 in (4 cm)...
Overview The Fairy Cichlid (Neolamprologus brichardi), also known as the Princess of Burundi, is an elegant Lake Tanganyika cichlid with long, white-edged fins. Found along the rocky shores of Burundi, Tanzania and the Democratic Republic of the Congo, mostly 16–82 ft...
Overview The Firemouth Cichlid (Thorichthys meeki) is a Central American cichlid known for its bright red-orange throat, which it flares to display. Native to lowland waters from southeastern Mexico, around the Yucatán Peninsula, to northern Belize and Guatemala....
Overview The Electric Yellow Cichlid (Labidochromis caeruleus) is a bright yellow mbuna from Lake Malawi. The yellow form comes from a short stretch of the northwestern shore, between Charo and Lion's Cove. Grows to about 3.9 in (10 cm) standard length. One of the...
Overview The Endler's Guppy (Poecilia wingei) is a tiny, brilliantly colored livebearer related to the common guppy. Native to lagoons in northeastern Venezuela, such as Laguna de Patos. Males grow to about 1 in (2.5 cm) standard length. Females are larger. Hybridizes...
Overview The Platinum Guppy is a metallic white strain of the common guppy (Poecilia reticulata). Wild guppies come from northeastern South America and the southern Caribbean, including Venezuela, the Guianas and Trinidad. Females grow to about 2.4 in (6 cm). Males...
Overview The Honey Gourami (Trichogaster chuna) is a small, peaceful gourami. Breeding males turn honey-orange with a dark throat. Native to the Ganges and Brahmaputra basins of northern India and Bangladesh. Grows to about 2.2 in (5.5 cm) standard length. A good...
Overview The Pindani Cichlid (Pseudotropheus socolofi), also called Eduard's mbuna, is a powder-blue Lake Malawi mbuna. Native to the Mozambique coast of Lake Malawi, between Cobue and Tumbi Point. Grows to about 5 in (11.5 cm) standard length. An albino form is also...
Overview The Pearl Cichlid (Geophagus brasiliensis), also called the pearlscale or mother-of-pearl cichlid, is a robust eartheater with iridescent spangled scales. Native to coastal rivers of eastern and southern Brazil and Uruguay. Grows to about 10 in (25 cm)...
Overview The Pearl Gourami (Trichopodus leerii) is a graceful gourami covered in pearly white spots. Breeding males develop a deep orange throat. Native to lowland swamps of Thailand, Malaysia, Borneo and Sumatra. Grows to about 5 in (12 cm) standard length. Hardy,...
Overview The Paraguay Eartheater (Gymnogeophagus balzanii) is a hump-headed South American cichlid that sifts sand for food. Native to the Paraná and Uruguay basins in Brazil, Paraguay, Argentina and Uruguay. Grows to about 8 in (20 cm) standard length. Best for...
Overview "Otocinclus" or "oto" covers several small algae-eating catfish. The one sold most often is probably Otocinclus macrospilus. Shipments are often mixed species. O. macrospilus comes from the upper Amazon in Peru, and possibly Colombia and Ecuador. Grows to...
Overview The Opaline Gourami is a captive-bred color form of the three spot gourami (Trichopodus trichopterus). It has a marbled blue pattern. Wild three spot gouramis live in slow, weedy lowland waters of the Mekong basin and Southeast Asia. Grows to about 6 in (15...
Overview The Oscar (Astronotus ocellatus) is a large, intelligent South American cichlid, also called the velvet or tiger oscar. Widespread in the Amazon region, usually in slow or still forest waters. Grows to about 14 in (35 cm) standard length. Typically lives...
Overview The Kuhli Loach is a slender, eel-like loach with orange and dark bands. It is sold as Pangio kuhlii. Most trade fish are actually Pangio semicincta from Peninsular Malaysia, Sumatra and Borneo. True P. kuhlii is from Java and is rarely exported. Grows to...
Overview The Mexican Tetra (Astyanax mexicanus) is best known in its blind cave form, the blind cave tetra. The species ranges from Texas and New Mexico through Mexico to Guatemala. The eyeless form lives only in Mexican caves. Grows to about 3.7 in (9.5 cm) standard...
Overview The Kribensis (Pelvicachromis pulcher), or krib, is a colorful West African dwarf cichlid. Females show a cherry-red belly. Native to Nigeria and Cameroon, in still and slow, heavily vegetated waters. Grows to about 3.9 in (10 cm) standard length. Most fish...
Overview The Kenyi Cichlid (Pseudotropheus lombardoi, also listed as Maylandia or Metriaclima lombardoi) is a Lake Malawi mbuna. Males are yellow and females are blue with dark bars, which is unusual among mbuna. Found naturally only at the Mbenji Islands and Nkhomo...
Overview The Red Wagtail Platy is a red strain of the southern platyfish (Xiphophorus maculatus) with black fins and tail. Wild platies live in streams and rivers on the Atlantic coastal plain of Mexico, Guatemala, Belize and Nicaragua. Grows to about 2 in (5 cm)...
Overview The Red Shoulder Severum (Heros sp. "Rotkeil") is a severum from Brazil with a red patch behind the gills. Its exact identity is unclear. It is often linked to Heros efasciatus. Severums in general come from slow rivers and floodplain lakes of the Amazon....
Overview The Zebra Loach (Botia striata) is a small botiid with fine yellow and dark stripes. Native to the Western Ghats region of southern India, described from the Tunga River. Grows to about 3.5 in (9 cm) standard length. Probably the best Botia for general...
Overview The Yoyo Loach is usually sold as Botia almorhae. Its pale body has dark markings that can look like the letters "YOYO." Many trade fish may be B. lohachata or related species. The true appearance of B. almorhae is unclear. Native to northern India and Nepal....
Overview The X-Ray Tetra (Pristella maxillaris) is a semi-transparent tetra with black, yellow and white fin markings. Native to coastal waters of Venezuela, the Guianas and northern Brazil. Grows to about 1.8 in (4.5 cm) standard length. Commercially bred and one of...
Overview The Trimac Cichlid (Cichlasoma trimaculatum, also listed as Amphilophus trimaculatus) is a large, colorful Central American cichlid. Native to the Pacific slope of western Mexico, Guatemala and El Salvador. Seriously Fish gives a maximum of 16 in (40 cm)....
Overview The Serpae Tetra (Hyphessobrycon eques), also called the jewel or callistus tetra, is a red tetra with a black shoulder spot. Found through much of the Amazon and the Río Paraguay. Grows to about 1.6 in (4 cm) standard length. Feeding Likely omnivorous....
Overview The Sailfin Pleco (Pterygoplichthys gibbiceps) is a large suckermouth catfish with a tall dorsal fin and a leopard-like pattern. Native to the Amazon and Orinoco basins in Brazil, Ecuador, Peru and Venezuela. Can reach around 18–20 in (45–50 cm). Feeding An...
Overview The Sailfin Molly (Poecilia latipinna) is a large molly. Males have a tall, sail-like dorsal fin. Native to the southern United States and Mexico, from the Carolinas to Veracruz, often in coastal and brackish waters. Grows to about 5 in (12.5 cm) standard...
Overview The Yucatan Sailfin Molly (Poecilia velifera), also called the giant sailfin molly, is the largest of the sailfin mollies. Mature males carry a huge, sail-shaped dorsal fin. Wild fish come only from southeastern Mexico, in the Yucatán and Quintana Roo region...