Family Belontiidae
gouramies and labyrinthfishes

The Belontiidae family, commonly known as gouramies, is composed of approximately 12 genera and 46 species, and is the largest and most diverse family in the Anabantoidei suborder. Gouramies are restricted to fresh water and are capable of inhabiting stagnant, low-oxygen areas due to the existence of an air-breathing organ called the labyrinthine (in Physical Description below). In addition, the Belontiidae family contains some of the most popular fish in the aquaria trade. One species, Betta splendens (Siamese fighting fish), has been in cultivation for over 100 years and captive individuals scarcely resemble the wild variety (see Economic Importance for Humans). Due to their pugnacious behavior, many gouramies have been used in behavioral studies as well (see Behavior). (Berra, 2001; Nelson, 1994; Wheeler, 1985)

All members of the Belontiidae family inhabit freshwater and are indigenous to Africa and Southern Asia. They can be found in Pakistan, India, China, Korea to the Malay archipelago, Indonesia and Borneo. However, due to their popularity in the aquarium trade and ease of transport, belontiids are frequently shipped far beyond their natural range. Several species that now live in the Philippines and United States originally escaped from the aquarium trade (Lever 1996 from Berra 2001 pg. 480, 487). (Berra, 2001; Nelson, 1994)

Gouramies are uniquely adapted to the stagnant waters of tropical areas. They inhabit swift streams, the backwaters of large rivers, brackish lagoons, and potholes. They are most common in stagnant areas with dense aquatic or overhanging vegetation. With the ability to breathe air directly from the atmosphere, gouramies are able survive in marginal to anoxic waters. (Graham, 1997; Moyle and Cech, 2000; Nelson, 1994; Wheeler, 1985)

Liem (1963) established three subfamilies, representing the major evolutionary lines of the Belontiidae family: Belontiinae (combtail gouramies), with one genus and two species, Magropodinae (Siamese fighting fishes, paradisefishes), with seven genera and approximately 32 species, and Trighogastrinae (gouramies), with four genera and about 13 species. (Berra, 2001; Nelson, 1994)

Gouramies are characterized by a distinct physical adaptation to stagnant waters, which is the labyrinthine organ. In this organ, located above the gill chamber, intricate, vascularized tissue stores air and allows gouramies to gulp air directly from the atmosphere. Additionally, gouramies have a long body cavity, allowing the swimbladder to extend into the tail. (Froese, Pauly, and Woodland, 2003; Johnson and Gill, 2002; Moyle and Cech, 2000)

Most gouramies are small (10 cm or less) and have elongate and cylindrical bodies. Others are deep-bodied and compressed. Gouramies have rounded tails and the anal fin base is much longer than the dorsal fin base in most species. In some gouramies, the first ray on the pelvic fin is elongated and is used as a tactile (touch-sensing) organ. After extensive breeding in captivity, the color and fin form have changed considerably in some gouramies. Sexual dimorphism has been reported for some members of this family. (Berra, 2001; Moyle and Cech, 2000)

One of two distinct physical features is the labyrinthine organ located above the gill chamber, which allows gouramies to breathe atmospheric air by capturing air bubbles from the surface water and holding them in the labyrinthine organ until they are expelled through the gill covers. “This unique organ is formed of highly vascularized, convoluted tissue, supported by an enlarged dorsal element of the gill arches” (Johnson, G.D. and A.C. Gill 1998). The bubbles taken in by gouramies are also important in hearing. Air bubbles are stored adjacent to membranous windows on either side of the cranium, which contains the inner ear. Slight vibrations picked up by the air bubble are easily transmitted to the inner ear through this membranous window. The second feature is a long body cavity that allows the swimbladder to extend into the caudal region. (Click here to see a fish diagram). (Johnson and Gill, 2002; Moyle and Cech, 2000)

After spawning, female gouramies release their eggs into the water. The eggs are gathered by the male and left in a nest near the surface until fry hatch. (Moyle and Cech, 2000)

No specific information was found concerning lifespan or longevity for this family.

Members of the Betta (fighting gouramies) genus have been used extensively in behavioral studies. Male fighting gouramies are extremely belligerent toward each other and they are often bred to fight, as with the fighting cocks. Talking gouramies use the air-breathing organ (labyrinthine) to produce a croaking sound, which is used in establishing territories and dominance hierarchies. Additionally, some gouramies use an elongated pelvic fin ray in exploratory behavior. The ray is directed forward to gather information about the fish’s surroundings or sense another individual as it approaches. Another interesting behavior of gouramies is the socially controlled synchronous air breathing. Groups of individuals in both Trichogaster and Colisa come to the surface and gulp air simultaneously in a temporary school to lessen the chance of predation while surfacing. (Berra, 2001; Graham, 1997; Helfman, Collete, and Facey, 1997)

Gouramies use several forms of communication: Talking gouramies use croaking to communicate, a modified pelvic fin ray is used as a tactile organ, and chemical signals are used during mating. The former two are described in more detail in the Behavior section and the latter is discussed in Reproduction. (Graham, 1997; McKinnon and Liley, 1987)

Members of the genera Belontia, Trichopsis, and Macropodus are omnivores, while Trichogaster is primarily herbivorous, and Betta and Colisa are carnivorous, feeding on shrimp, fish and insects in or out of water. Colisa uses the same technique as archerfishes to prey on insects just above the water. Bullets of water are created by compressing the gill covers and forming a groove using the tongue and palate. The fish “shoots” insects out of overhanging vegetation with these bullets and eats them when they hit the water. (Graham, 1997; Helfman, Collete, and Facey, 1997)

One impact of predation on gouramies is the frequency and location of atmospheric air breathing. In the presence of predatory birds or fish, some gouramies hide in mats of aquatic vegetation and surface less frequently. Other gouramies form temporary schools when they come up in order to deter predators. This “synchronous air breathing” is discussed above in Behavior. (Graham, 1997)

Because gouramies are uniquely adapted to harsh conditions, such as hypoxia (water without oxygen) and desiccation, they are an important predator in the stagnant and intermittent waters of Asia. In addition, air breathing serves to protect gouramies from excessive water pollution so they play an important role in the biological control of insects in urban areas. This is discussed further in Economic Importance for Humans. (Graham, 1997; Wheeler, 1985)

No specific information was found concerning any negative impacts to humans.

Many gouramies are popular aquarium fishes because of their bright coloration, small size, and interesting reproductive behaviors. Members of the genus Betta, fighting fishes, have been used extensively in genetic and behavioral studies. Fighting fishes are also bred for entertainment and gambling in some countries. Finally, members of the genus Trichogaster have been cultured in ponds as food fish. (Berra, 2001; Helfman, Collete, and Facey, 1997; Johnson and Gill, 2002)

Experiments with Macropodus cupanus show that breathing air at the surface instead of consuming oxygen entirely from water lessens the absorption of toxic pollutants, which makes gouramies more effective in the biological control of insects. For example, mosquito larvae form the main diet of fish in the Betta genus. Each adult consumes approximately 10,000 to 15,000 mosquito larvae each year, significantly reducing the mosquito populations and mosquito-related illnesses. (Graham, 1997; Wheeler, 1985)

There are 11 species of concern within the genus Betta. Of these, three are listed as critically endangered, one is listed as endangered, and seven are listed as vulnerable. Additionally, Parosphromenus harveyi is listed as endangered, and Belontia signata and Malpulutta kretseri are listed as low risk depending on conservation efforts. (The World Conservation Union, 2002)