|Wednesday, 9-Nov-2005 00:00
New Fish Species Studied for Aquaculture Potential by Aquaculture CRSP Researchers
By Dhirendra Prasad Thakur, Asian Institute of Technology
Climbing Perch (Anabas testudineus)
The climbing perch (Anabas testudineus) is a fish of tropical fresh waters of Asia and the Far East. The fish derives its name from the widely held belief that it can climb on trees, but this is actually a result of faulty observation.
A. testudineus is a very hardy fish. It is mostly caught from swampy and marshy tracts, as well as derelict pits, pools, and puddles that continue drying up during summer months. In its natural habitat, the fish can "walk" over dry land for some distance using its operculum and pectoral fins.
A. testudineus is in the family Anabantidae. It has an elongated body, with broad anterior and head, while the posterior is compressed. The dorsal side, and dorsal and caudal fins, are greenish to dark grey, while the belly, pectoral, and anal fins are pale yellow-colored. At the base of the caudal fin, a dark spot is present. A. testudineus is an obligatory air-breathing fish. In addition to four pairs of gills, it bears accessory respiratory organs‹one pair of labyrinthine and respiratory membranes within the suprabranchial chamber. The fish is highly esteemed for its fine flavor and prolonged freshness out of water. The maximum recorded length is 26 cm.
Seed of A. testudineus can be collected from nature or obtained under controlled conditions. A. testudineus is notorious for migrating and breeding into prepared carp nurseries. This habit is advantageously used for seed production. Gonad maturity in A. testudineus manifests with early rains, and the retrogression is noticed abruptly from September. Breeding takes place only after rain fully sets in and fills ditches. According to Besra (1997), breeding season lasts between the middle of April to the middle of June. In the laboratory, end of breeding was delayed as late as September. Induced breeding by hypophysation was successfully performed. Water temperature of 28 ± 1C and darkness were important environmental factors for successful spawning. A female weighing about 50 g produces about 20,000 eggs. Eggs float in an upside-down position at the surface. Feeding commences from the second day. Ciliates, flagellates, and other such minute zooplankton form the chief food of food of larvae at this stage. food or larvae at this stage.
A. testudineus is omnivorous but shows definite preference for insects. The scope of its natural food, however, is very wide. It can vary from a diet of filamentous algae to purely carnivorous. Pandey (1987) mentions that the alimentary canal structure indicates the fish has a tendency towards carnivorous and predatory habits. This fish feeds within the water column as well as on the bottom and has a short and slightly coiled intestine (Mookerjee and Majumdar, 1946).
A. testudineus can be cultured in monoculture, or in polyculture systems with Clarias batrachus or Heteropneustes fossilis or both. It can also be grown in composite fish culture ponds together with carps. Since the fish has a tendency to ³walk out² of ponds, dykes should be sufficiently steep (75 degrees or more) to prevent escape of the fish.
Besra, S., 1997. Growth and bioenergetics of Anabas testudineus (Bloch): An air-breathing climbing perch of south-east Asia. Narendra Publishing House, Delhi, India, 139 pp.
Mookerjee, H.K. and S.R. Majumdar, 1946. On the life history, breeding and rearing of Anabas testudineus (Bloch). J. Dep. Sci. Cal. Univ., 2: 101140.
Pandey, A., 1987. Some aspects of ecophysiology of Anabas testudineus (Bloch). Ph.D. thesis, Bhagalpur. University, Bhagalpur, India.