LABYRINTH FISHES: Anabantoidei

PHYSICAL CHARACTERISTICS

Labyrinth fishes are about 1 to 24 inches (2.5 to 60 centimeters) long and have a special air-breathing organ called the labyrinth (LAB-uh-rinth). Most species have a space in their head bones that sharpens their hearing. The swim bladder, an internal sac that fishes use to control their position in the water, branches into two long pouches. Many species are beautifully colored.

GEOGRAPHIC RANGE

Labyrinth fishes live in Africa and Asia. Several species have been released accidentally to areas outside their natural range.

HABITAT

Many labyrinth fishes live in still bodies of water with thick plant life, but some live in cool, fast mountain streams. Most labyrinth fishes can live in water with a low oxygen level.

DIET

Most labyrinth fishes eat small invertebrates (in-VER-teh-brehts), or animals without backbones, and algae. Algae (AL-jee) are plantlike growths that live in water and have no true roots, stems, or leaves. Some species eat small fishes.

BEHAVIOR AND REPRODUCTION

Labyrinth fishes rise to the water surface to exchange the air in their air-breathing organ. Some leave the water and travel over land to nearby bodies of water. Some labyrinth fishes release free-floating eggs and do not take care of them. Others build bubble nests and guard floating eggs and larvae (LAR-vee), or the early stage of the animal that must change form before becoming adults. Some bubble nests consist of only a few bubbles, but others are large. In some species of labyrinth fishes, the young develop in a parent's mouth. Some species release sticky eggs on the bottom of their habitat.

LABYRINTH FISHES AND PEOPLE

The larger species of labyrinth fishes are farmed for food. The smaller, colorful labyrinth fishes are used in aquariums.

CONSERVATION STATUS

The World Conservation Union (IUCN) lists three species of labyrinth fishes as Critically Endangered, three as Endangered, seven as Vulnerable, and the two as Conservation Dependent. Critically Endangered means facing an extremely high risk of extinction in the wild. Endangered means facing a very high risk of extinction in the wild. Vulnerable means facing a high risk of extinction in the wild. Conservation Dependent means if the conservation program were to end, the animal would be placed in one of the threatened categories.

CLIMBING PERCH (Anabas testudineus): SPECIES ACCOUNTS

Physical characteristics: Climbing perch are about 10 inches (25 centimeters) long. The body shape ranges from oval in profile and narrow from side to side to long and slightly round in cross-section. The bones of the gill cover have strong spines. The dorsal and anal fins are long and have strong spines. The dorsal (DOOR-suhl) fin is the one along the midline of the back. The anal (AY-nuhl) fin is the one along the midline of the belly. The scales are rough. The air-breathing organ is very large. The body is light beige with darker spots. On each side of the fish there is a large black spot between the gill cover spines and another on the tail.

Geographic range: Climbing perch live in Asia. They have been accidentally released in the United States.

Habitat: Climbing perch live in all types of fresh water.

Diet: Climbing perch eat plants, invertebrates, and small fish.

Behavior and reproduction: Climbing perch can travel over land. They use the spiny bones on their gill covers and side-to-side wriggling of the body to move themselves forward. These fish drown if they cannot rise to the surface to gulp air. To survive drought they bury themselves in the mud of drying-up water bodies. Climbing perch do not take care of their eggs or their young. Eggs hatch twenty-four hours after being released.

Climbing perch and people: Climbing perch is a popular food fish in Southeast Asia.

Conservation status: Climbing perch are not threatened or endangered. ∎

SIAMESE FIGHTING FISH (Betta splendens): SPECIES ACCOUNTS

Physical characteristics: Siamese fighting fish reach a length of about 2 inches (6 centimeters). They have a long tube-shaped body. Some species have large fanlike dorsal, anal, and tail fins. Wild Siamese fighting fish have a bluish body and blue and red fins. There are two shiny marks on the gill cover. Males have larger fins and are more brightly colored than females.

Geographic range: Siamese fighting fish live in Southeast Asia and in areas where they have been accidentally released, such as Florida, in the United States.

Habitat: Siamese fighting fish live in standing water with dense plant life, especially rice paddies and canals. They may dig into the mud when the water level is low and can survive weeks in a small cocoon-like structure made of mud and probably mucus.

Diet: Siamese fighting fish eat invertebrates such as animal plankton and insect larvae.

Behavior and reproduction: Siamese fighting fish are well known for their aggressive behavior, especially against males in their own species. In small tanks, males fight until one of them dies. A male Siamese fighting fish builds a floating nest of bubbles and aggressively defends the territory around it. He mates with a female under the nest, placing sperm on the eggs as she lays them. The male then takes the eggs one at a time into his mouth and shoves them into the nest. The eggs hatch about thirty-six hours later, and the larvae swim free on the fourth day.

Siamese fighting fish and people: Siamese fighting fish are popular in aquariums.

Conservation status: Siamese fighting fish are not threatened or endangered. ∎

FOR MORE INFORMATION

Books:

Ricciuti, Edward R. Fish. Woodbridge, CT: Blackbirch, 1993.

Web sites:

"The Fish That Climbs Trees." World Wildlife Fund. http://www.panda.org/news_facts/education/middle_school/species/perch.cfm (accessed on November 6, 2004).

"Labyrinth Fish: Anabantoidei." Mekong River Commission. http://www.mrcmekong.org/pdf/Anabantoids.pdf (accessed on November 6, 2004).

"Siamese Fighting Fish." All Science Fair Projects. http://www.all-science-fair-projects.com/science_fair_projects_encyclopedia/Siamese_fighting_fish (accessed on November 6, 2004).