Principles of Genetics and Breeding

15.1.1 Fish seed certification and quarantine procedures

Freshwater aquaculture contributes more than 50 percent to the total aquaculture production in majority of the leading aquaculture producing countries in Asia.

Lack of quality fish seed supply is often documented as a bottleneck for freshwater aquaculture development in rural areas of many countries. Fish seed for stocking in aquaculture systems are either collected from wild resources, produced in hatcheries or imported from other countries.

Among the species used in seed production silver carp, grass carp, common carp, Indian major carps, Thai pangus, Thai koi, Nile tilapia and the Genetically Improved Farmed Tilapia (GIFT) are predominant. Fish species used in seed production for freshwater aquaculture in different Asian countries are given in Table 1.

Some fish are bred for conservation purposes, e.g. Mahseer and black carp in Bangladesh. Red tilapia is being used for seed production under very limited scale. Polyculture is the normal practice with stocking regimes and densities varying with feed availability, water quality and market price.

Before the introduction of hypophysation technique (1960s) in Chinese carps and Indian major carps, aquaculture was mainly a wild seed dependent activity. Riverine seed collection was the main source of seed for carps, contributing 91.67 percent and 97.5 percent to the total fish seed production during mid-1960s in India and 1980s in Bangladesh, respectively.

The vast stretches of low-lying lands bounded by embankments that are filled with run-off from extensive catchment areas during the monsoon have been traditionally used in India as ‘natural hatcheries’ to produce wild seed of carps.

The sudden influx of rainwater into these systems provides a stimulus for the fish to spawn. This natural way of induction to spawn accounted for a major portion of fish seed during the 1960s to 1980s in India. In Bangladesh, carp spawns and fry were collected during the monsoon season from different river systems, while fertilized eggs collected were incubated in earthen pits in the river banks for hatching. This method of hatching yielded low hatching and higher mortality rates.

Table 1. Fish species used in seed production for freshwater aquaculture in different Asian countries

Sl. No.	Country	Species
1	Bangladesh	Catla catla, Cirrhinus cirrhosus, C. ariza, Labeo rohita, L. calbasu, L. bata, L. gonious,Puntius sarana, Hypophthalmicthys molitrix,Cyprinus carpio, Ctenopharyngodon idella, Aristichthys nobilis, Barbonymus gonionotus, Pangasius sutchi, Oreochromis niloticus, Anabas testudineus, Clarias batrachus, Heteropneustes fossilis, Ompok pabda, Mystus cavasius, Mylopharyngodon piceus, Tor putitora, O mossambicus x O. niloticus hybrid.
2.	China	C. idella, H. molitrix, A. nobilis, C. carpio, O. niloticus, Mylopharyngodon piceus, Barbodes goniotus, Cirrhinus molitorella, Cirrhinus mirigala, L. rohita, Catla catla, Clarias sp., Channa sp.
3.	India	C. carpio, C. idella, H. molitrix, A. nobilis, L. rohita, C. catla, C. mrigala.
4.	Philippines	Oreochromis niloticus
5.	Sri Lanka	C. idella, H. molitrix, A. nobilis, L. rohita, C. catla, C. mrigala, Chanos chanos
6.	Thailand	Clarias macrocephalus x C. gariepinus¸ O. niloticus, Barbodes gonionotus, Trichogaster pectoralis, Macrobrachium rosenbergii, Pangasianodon hypophthalmus, Channa striaus, C. carpio, Trionyx sinensis

With the advent of induced breeding technology of Indian and Chinese major carps, it became possible to obtain quality seed for aquaculture. This resulted in an increased reliance on induced breeding for obtaining quality fish seed. At present, induced breeding accounts for most of the seed produced by many species throughout Asia.

Although, artificial propagation is the main means of seed production, seed collected from the wild are mainly used for maintaining the quality of broodstocks.

Broodstocks used for artificial propagation are usually raised in captivity using seed from the wild or from breeding centers where good natural stocks are maintained.

Private sector hatcheries and nurseries, particularly hatcheries and fry nurseries operated by farmers constitute a significant source of fish seed which far exceeds the public sector contribution.