Types of Tropical Fish: Popular Species and Water Temps

Tropical fish are fish from tropical waters, and the term is used mostly for aquarium fish; Wikipedia stresses it is a general label, not a scientific group. Freshwater species dominate the hobby because tap water is easy to use, while a marine tank needs sea salt and careful salinity control (Wikipedia).

Where they come from matters when you buy. Most freshwater tropical fish sold today are farmed in Asia and Florida, which keeps them cheap. Marine tropical fish are mostly caught wild on coral reefs, because few species are bred in captivity regularly, so they cost more and are harder to keep (Wikipedia). Coral reefs cover less than 1% of the ocean surface yet hold about 25% of all marine fish species (Wikipedia).

Sizes, temperatures and pH below are FishBase's figures for each species in the wild:

• [Neon tetra](/lookup/popular-fish/neon-tetra) (Paracheirodon innesi): 2.5 cm; 20-26°C; pH 5.0-7.0; blackwater and clearwater streams of the Solimões basin in South America. FishBase calls it the most commercially popular aquarium fish
• [Guppy](/lookup/popular-fish/guppy-fish) (Poecilia reticulata): females 6 cm, males 5 cm; 18-28°C; pH 7.0-8.0; Venezuela, Trinidad, northern Brazil and the Guianas
• [Platy](/lookup/popular-fish/platy-fish) (Xiphophorus maculatus): females 6 cm, males 4 cm; 18-25°C; pH 7.0-8.0; Veracruz, Mexico, to northern Belize
• Cherry barb (Puntius titteya): 5 cm; 23-27°C; pH 6.0-8.0; found only in the Kelani to Nilwala basins of Sri Lanka and listed as Vulnerable (IUCN, assessed 2019, via FishBase)
• Harlequin rasbora (Trigonostigma heteromorpha): 5 cm; 22-25°C; pH 5.0-7.0; forest streams of the Malay Peninsula, Singapore and Indonesia
• Bronze corydoras: 7.5 cm; 25-28°C; pH 6.0-8.0; Colombia and Trinidad to the La Plata basin. FishBase now files it as Osteogaster aenea, formerly Corydoras aeneus; see our corydoras page

Other tropical freshwater fish on this site: betta, zebra danio, freshwater angelfish, clown loach, oscar, African cichlids and the wider tetra group.

Beginner lists rarely show this, but you can work it out from FishBase's ranges: a mix of fish is comfortable only where all their ranges overlap.

• Neon tetra + harlequin rasbora + cherry barb: temperature overlap 23-25°C, pH overlap 6.0-7.0. A workable soft-water community
• Neon tetra + bronze corydoras: only 25-26°C overlaps, so keep the tank at the warm end of the neon's range
• Guppy + platy: 18-25°C and pH 7.0-8.0, a good hard-water pair
• Neon tetra + guppy: temperatures overlap widely (20-26°C) but pH meets only at 7.0, because neons come from soft, acidic water and guppies from harder, alkaline water

These are ranges for wild fish; farmed fish are often more tolerant, so ask the seller what water they were raised in.

• [Ocellaris clownfish](/lookup/popular-fish/ocellaris-clownfish): the Nemo fish, widely captive-bred
• Regal blue tang (Paracanthurus hepatus): the 8th most traded aquarium fish in the world, with about 95,000 imported in 2011; first bred in captivity in 2016 (Wikipedia)
• Royal gramma (Gramma loreto): about 8 cm, purple at the front and yellow at the back; from the western Atlantic and Caribbean (Wikipedia)
• Four-stripe damselfish (Dascyllus melanurus): 3 to 4 inches, black and white bars, very aggressive as an adult (Wikipedia)
• Moorish idol (Zanclus cornutus): striking but notoriously difficult to keep, needing over 100 gallons (Wikipedia)

For the characters from the film, see Finding Nemo fish names; for the tang family, see surgeonfish.

Aquarium Co-Op's beginner list names rasboras, tetras, corydoras, platies, bettas, barbs, the Bolivian cichlid, kuhli loaches and angelfish, with some caveats: tetras, rasboras and barbs in groups of six or more; corydoras in groups of three to six of one species; angelfish need 55 gallons or more; and bettas cannot share a tank with other bettas. The Bolivian cichlid is listed at 72-79°F and pH 7.0-8.0.

The same list includes the common goldfish, which is not a tropical fish. FishBase says goldfish tolerate 0-41°C but live better in cold water and need a cold winter for proper egg development, and Aquarium Co-Op gives 12 to 14 inches and 30 gallons per fish. Keep goldfish apart from a heated tropical tank. For very small tanks, see small aquarium fish.

Aquarium fish released outdoors can become invasive where the climate lets them survive. FishBase records that guppies, widely introduced for mosquito control, had rare to non-existent effects on mosquitoes but negative effects on native fish, and Wikipedia reports that discarded flowerhorn cichlids have become an invasive pest in Singapore and Malaysia. Rehome unwanted fish through a shop or club instead.

Shop labels are often trade names, and one name can cover several species. A clear side-on photo through the glass, with the fins spread, is enough for FishLens to suggest the species, and then you can look up its temperature and pH before it goes into your tank.

Research and drafting for this page were assisted by AI and checked line by line against the sources listed below. Every number names the organisation it comes from; where sources disagree we say so instead of picking one silently. Prices and counts are given with the date we checked them. If you find an error, tell us and we will correct it.