For profitable fish culture, it is necessary to select, such species of fish, which can utilize the natural and artificial food to the maximum, extend and grow rapidly to a large size. Species that fulfill the following conditions can considered suitable for culture.
It should have a fast growth rate.
It should be able to feed on the natural food of the pond efficiently and artificial food to maximum advantage.
It should be hardy and resistant to diseases.
It should be able to survive under temporary bad water conditions and hardship of transport.
It must be prolific breeder and easy to breed in ponds.
It should not be predaceous, and preferably herbivorous in habit.
The fish should be tasteful and with high nutritive value.
Species that can be cultured together without competing with each other are preferable for maximum utilization of water cultivable species can be three types.
Indigenous or the native fresh water fishes the carps.
A few salt-water fishes that the acclimatized to fresh water likes the chanos and mullets.
Exotic fish imported from outside the areas or the country like the mirror carp, Chinese carp, Tilapia etc.
When the indigenous fishes are uneconomical or unfit for culture, suitable exotic species are introduced. None of the species can be called an ideal one for culture, as it may not possess all the desirable qualities. Carps are economically the most important fishes for culture as:
They feed on zoo-and phytoplankton, decaying weeds and debris and other aquatic plants, which are available in plenty in the ponds.
They are resistant to relatively high temperature and turbid water.
They can tolerate low oxygen content.
They have a fast of growth and attain a reasonably large size in a short time.
They breed profusely.
The important cultivable species of India are called the major carps. These are Labeo, Rohita, Calta, Cirrhina, Mrigala, Labeo calbasu, Labeo fimbrikatus, L.Bata, etc. besides these some exotic species like Cyprinus Carpio, Ctenopharyngodon idella (the grass carp), Hypopthalimlimichthya inolitirix (the Chinese carp).Osphranenus goramy, Tikopia mossambica etc. are popular with the fish culturists.
A knowledge of relative growth, maturation and fecundity of fishes is necessary before planning fish culture. Growth of fish depends on the population, density and availability of food. The attainment of sexual maturity also depends on the abundance of food and duration of feeding. Besides these, temperature, photoperiod and several other factors influence maturation of gonads.