DOMESTICATION IN FISHES

Clutton-Brock (1999) - Domestic animal -“One that has been bred in captivity for purposes of economic profit to a human community that maintains total control over its breeding, organization of territory, and food supply”.

CHARACTERS OF A DOMESTICATED ANIMAL The individual is valued and kept for a specific purpose, Its breeding is subject to human control, Its behaviour is different from that of the wild ancestor, Its morphology and physiology exhibit variations never seen in the wild and Some individuals at least would not survive without human protection.

DOMESTICATION OF FISHES Domestication effects are observed in fishes within two generations after removal from the natural environment. They perform better in the aquaculture environment than wild strains. In channel catfish (Ictalurus punctatus) an increased growth rate of 3 to 6 percent/ generation was observed. Commonwealth Scientific and Industrial Research Organization (CSIRO) in Australia and the shrimp culture industry has resulted in successful captive breeding of Penaeus japonicus.

DOMESTICATED AQUARIUM SPECIES Guppy -Poecilia reticulata. Swordtails -Xiphophorus hellerii. Platies Xiphophorus maculatus. Mollies Poecilia sp. Neon tetra Paracheirodon innesi. Discus and angelfishes (Cichlidae). Zebrafish - Danio rerio.

DOMESTICATED FARMED SPECIES Rainbow trout-Oncorhynchus mykiss. Channel catfish -Ictalurus punctatus. Salmonids. Chinese and Indian major carps (Cyprinidae). Tilapias (Cichlidae). Sturgeons (Acipenseridae).

COMMON CARP DOMESTICATION Change of torpedo-shaped body into a deep, laterally compressed and hunchbacked body. Production of scaled carp, line carp, mirror carp, and leather or naked carps. Utilization of supplementary food, better growth in ponds. Production of longer intestines due to utilization of vegetable food. (Intestine of wild common carp 15 to 25% shorter than domesticated carp).

The swim bladder’s anterior chamber is larger and the posterior chamber smaller. (Proportion is 61 : 39 for the wild and 90 : 10 for the domesticate). Emergence of red and white koi, red, black and white, black koi with white and red.

DOMESTICATION OF GOLDFISH The goldfish was domesticated in China. Eggs, embryos and larvae were exposed to biological, physical and chemical stresses to cause epigenetic alterations in their ontogenies leading to the development of new ‘monsters’ that survived longer.

Golden helmet, Golden saddle, Stork’s pearl, Brocaded back, Seven stars, Red head-and-tail, Purple eyes, Snow eyes, The three tails, four tail, nine tail, Bulging eyes, The bicaudal, The dragon eye. By artificial selection lion-head, goose head ,the narial bouquet goldfish were produced.

DOMESTICATED AQUARIUM FISHES Guppies -triangle (the caudal fin is triangular), fantail, veil tail, banner tail, lyre tail, top sword, bottom sword, double sword, spear tail, round tail, spade tail. The long-tailed and most colourful fish can’t survive in the wild and, are considered truly domesticated. By hybridization and artificial selection, Xiphophorus variatus, X. helleri, X. maculatus were produced.

CONCLUSION Only guppies and neon tetra in modern aquarium culture are considered as domesticated. The zebra fish, will soon be domesticated. Chinese and Indian carps, grass carp, silver carp, bighead carp, catla, rohu, mrigal, calbasu, salmonids, tilapias, basses, zanders or walleyes (Stizostedion sp.), tench Tinca tinca, Silurus glanis, walking catfish Clarias batrachus, sturgeons, rainbow trout, channel catfish have potential to become domesticated in the future.

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