The Rainforest cREMedia 1994 All Rights Reserved. FISH The variety of rainforest fish Tropical rainforests are usually associated with extensive waterways, and these warm freshwaters are home to a wide variety of fish species. Most freshwater aquarium species sold in the USA were originally derived from the tropical waters of South America, Africa or southeast Asia. In this chapter we describe some of the more interesting species to be found in rainforest environments. Characins Characins belong to the same group of fish as catfishes, loaches and minnows. There are over 800 species in Central and South America and 150 species in Africa. Characins include several species of piranha, 12-14 inch long fish that inhabit the Amazon and its tributaries. These silvery blue fish live in schools, and they have extremely sharp teeth which give a savage bite. Cichlids Related to perches, mackerel and tuna, the Cichlids are a family of tropical freshwater fish that live in Central and South America as well as in Africa. They include Tilapia, the largest group of African cichlids, as well as the beautiful Discuses, an Amazon dwelling family and the Pseudotropheus cichlids of Lake Malawi. Cyprinodontids These small fish are found in warm freshwaters, and include several families common in rainforest rivers. Guppies and Mollies. The guppy shown here is Poecilia reticulata from the north Amazon region. This fish has been introduced elsewhere to control mosquito larvae, and it is also a well-known aquarium fish. The four-eyed fish Anableps has eyes that are divided horizontally, and is capable of seeing both above and below water as it swims at the surface of rivers in Central and South America. Electric eels Electric eels belong to the family Gymnotidae, or electric fishes. These eels may measure up to 6 feet long and have no fins except for a single long anal fin. Special muscles running along the eels' body can produce enough energy to stun a human being - up to 650 volts of electicity. Labyrinth fishes These African and Asian freshwater fish are members of the family Anabantidae. These fish are also called labyrinth fish because they have a special respiratory organ called the labyrinth behind the eyes. This organ is used to extract oxygen from the water when the fish is at the surface. Labyrinth fish also have thread-like pectoral fins which are used as organs of taste and smell. The fish shown here is the three-spot gourami, found in the rainforest streams of South Vietnam, Thailand and Malaya. Snout fishes Snout fishes are only found in Africa: there are around 100 different species, and most of them have poor eyesight. Snout fishes live in muddy or marshy waters which offer limited visibility and these fishes have a built-in radar system which helps them find their way about. A weak electric field is generated by an organ in the tail, and this field alters depending on the fishes surroundings. By using this system these fish can navigate in almost total darkness. The fish shown here is a member of the family Gnathonemus, found in the Congo, East Africa and Cameroon. This species, Gnathonemus elephas, or the African Elephant Nose, has an elongated snout which it uses to search for worms and mosquito larvae. Snout fishes show a wide variation in the length of their snouts. Several species have a very reduced snout, which appears little more than a protruding lower lip. Ray-finned fishes Ray-finned fishes are large primitive fish. Two examples live in the Amazon basin: Arapaima grow up to 15 feet in length and are among the largest freshwater fish. Arawana are 2-3 feet in length and feed by jumping out of the water and catching insects. They are sometimes called 'water monkeys' by the local people. Male arawanas guard their young by holding them in their mouths. They cannot feed while brooding the young. Both arawanas and arapaimas are becoming rarer as their rainforest environment becomes depleted.