Tropical fish include fish found in tropical environments around the world, including both freshwater and salt water species. Tropical fish are popular as aquarium fish, due to their often bright coloration. In freshwater fish, this coloration typically derives from iridescence, while salt water fish are generally pigmented.
Fishkeepers often use the term tropical fish to refer particularly to those requiring fresh water, with saltwater tropical fish referred to as marine fish. Tropical fish kept for home aquaria include the following:
Single-species individuals born in captivity. The latter category includes lines selectively bred for special physical features, such as long fins, or particular colorations, such as albino.
Many marine tropical fish, particularly those of interest to fishkeepers, are the fish which live amongst or in close relation to coral reefs. Coral reefs form complex ecosystems with tremendous biodiversity. Among the myriad ocean inhabitants, the fish stand out as particularly colourful and interesting to watch. Hundreds of species can exist in a small area of a healthy reef, many of them hidden or well camouflaged. Reef fish have developed many ingenious specialisations adapted to survival on the reefs.
Coral reefs occupy less than one percent of the surface area of the world oceans, yet they provide a home for 25 percent of all marine fish species. Reef habitats are a sharp contrast to the open water habitats that make up the other 99% of the world's oceans.