‘Spawn’ is the name for the young fish about three days old that are available from hatcheries. Sometimes these young fish are also called hatchlings. The spawn of catla, rohu and mrigal is about 6-8 mm long. At this stage, the ‘yolk sac’ is absorbed, the mouth opened and the fins fully developed. Spawn are reared intensively, first to the ‘fry’ size and then to the ‘fingerling’ size. All the three stages are marketed and collectively called ‘seed’.

The “fast fingerling system” can produce advanced fingerlings about two months earlier than they are normally available from fish farms.  The farmer uses just one pond for continuous growing until fingerling size is reached, and fewer fish are stocked. A farmer with a small, seasonal pond can produce fingerlings in one month. These can then be sold for a high price because everyone wants fingerlings as early as possible.

The fingerling rearing pond, like the nursery pond, should be free from weeds and predators. Submerged weeds and predators are killed by mahua oilcake, which then acts as a good fertiliser. If there are no weeds, to kill predators and competitors quickly you can just add 100 kg of urea followed 24 hours later by 200 kg of fresh bleaching powder for a 1-ha area of a 1-m deep pond.

In watersheds, medium irrigation projects can be useful for aquaculture even though these water bodies are many times larger than ponds, and are basically built for irrigation or water storage. However, the full potential of these water bodies is not yet realised. Net pens or cages can be used to rear fingerlings in such environments.

It is best to stock advanced fingerlings in large ponds, tanks, and in both small and large reservoirs, since they can better escape predators and competitors. Seasonal ponds, often 0.10-0.15 ha and 1.5-1.8 m deep can be used as rearing ponds for raising advanced fingerlings. Low water levels at the end of the season will make netting and harvesting easy.

Everyone wants advanced fingerlings as early after the rains as possible. They fetch a good price and make marketable fish production possible in seasonal ponds. One way to produce early season advanced fingerlings is to grow them in perennial ponds and store them at high density with minimal feeding for the coming year. Whe such "stunted" fingerlings are stocked into ponds with good feed they grow fast and can be marketed in about 6-8 months.

Common carp is a foreign fish and there are several varieties. The variety used in Western Orissa is the fully scaled carp, which suits the tropical climate. Common carp lives and feeds near the pond bottom and can be grown with the Indian major carps, catla, rohu and mrigal as a 'polyculture' (which means growing many different types of fish together). It can also be grown alone, as a 'monoculture' in rice fields with high dykes that retain water.

These guidelines provide advice on producing fish seed of the Indian major carps in hapas within ponds to improve survival.

In this issue:

Nursery rearing of silver barb Puntius goniotus. Artemia enrichment and biomasss production for larviculture. Seed production of mud crab Scylla serrata in India. Macrobrachium on the southwest coast of India. Fish wastes in urban and suburban markets of Kolkata: Problems and solutions. Groups of poor women farming carps in leased ponds, Bangladesh. Lymphocystis disease and diagnostic methods in China. Mesocosm technology advances grouper aquaculture in northern Australia.

It was common to believe that fish cannot be cultured in seasonal ponds. However, fish can be produced in any pond of any size, anywhere in Orissa, provided that the water quality is good enough. A small and shallow pond that retains water for two months can be used for raising fry. A larger and deeper pond holding water for three to four months can be used for fingerling production.