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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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...