The problems encountered in bundh breeding are :
1. Sometimes it is difficult to coordinate the collection and hatching of large quantities of eggs at a time, particularly in the case of wet bundh breeding.
2. During egg collection from wet bundh, often unwanted fish spawn, and, predatory insect larvae, etc. are also collected.
3. In most cases, the hatching rate of eggs and survival of hatchlings upto the spawn stage have been poor, even when the fertilization rate of eggs was high. This could be improved by using modern hatchery techniques.
4. Presence of fairy shrimps (Streptocephalus sp. and Branchinella s) is in large numbers in dry bundhs particularly when breeding is late, i.e., three weeksof water accumulation during the collection of eggs. They can be controlled by sqjplying bleaching powder at the rate of 1 ppm on the first day of water accumulation,
5. Most of the dry bundhs primarily belong to the government. These are tasically meant for drinking water and irrigation purposes. Fish breeding in these bundhs is, therefore, a secondary activity. No control on the inflow and outflow af waters for fishery activities is possible.
6. The brood fish are mainly collected from the wild habitats for dry bundh breeding. Gillnets or cast nets are used for catching the brood fish thereby causing injuries to the brood fish.
7. Brood fish may carry some infection or injury.
8. When the rains are heavy after spawning is over the influx of water is so strong that much of the gonadal products are destroyed by mechanical injury.
9. Before the release of brood fish or at the time of spawning and development of the spawn, adequate attention is not paid to monitoring the water quality as regards dissolved gases, toxic substances and predatory organisms.
10. In the late monsoon with accumulation of more waters, some dry bundhs start overflowing, thus increasing the risk of loss of seed from the bundh.
11. In the post-monsoon months with receding water level, the fmgerlings are” exposed to the risk of predation by the birds.
12. In some dry bundhs having a uniformly flat basin, when the water is reduced to critical level, seed collection becomes difficult and there may be mortality due to rise in temperature and turbidity in shallow sheets of water caused by repeated netting operations.
13. Late harvest of fish seed with decreased amount of water further aggravates the problem of poaching.
14. The early major carps are voracious in their feeding habits. If adequate food is not made available to them they become cannibalistic, especially if there is a noticeable difference in the size grThis is especially true when brood fish-are released in batches.
15. Often, when the dry bundh is supporting a good number of fish seed, water is drained out for irrigation purposes. This may also cause loss of sizeable stock from the dry bundh.
16. In most cases the spawn is allowed to stay uncared for in the dry bundh under natural conditions. If in excess, the silt, predatory insects and copepodes cause heavy damage to the developing eggs and subsequently to the juvenile fishes.
17. When spawning occurs the water may recede to critical levels thereby exposing a large amount of eggs in the peripheral areas of dry bundh thus causing large scale mortality of spawn.
Economics
In an experiment in Nain Thallia, about 20 million eggs were produced per hectare. In Midnapore and Bankura. 75 lakhs of spawn was produced at a time, and 160-220 million spawn produced in a season. With the increasing pace in the creation of a large number of bundhs, it is necessary to mention that spawn production through dry bundhs, is quite economical. Many crops of seed can be easily obtained from one bundh in a season of 4 months. By utilising the rain water which would otherwise have been waste water, we can produce carp seed and reap good profits.
The bundhs are not only useful for fish breeding but also useful to culture fish after breeding. If the water is available for at least 6 months, those bundhs can be utilised to culture the fish. The fish seed of cultivable fishes can be introduced in the seasonal rain-fed bundhs and can be cultured for six months. Without providing supplementary feed and inorganic manures the yield can be about 1000 kg/ha/6 months. By providing supplementary feed and inorganic manure the yield can be increased to about 2500 kg/ ha/6 months. It indicates that the bundhs are useful for both breeding and culture, and are highly profitable.
Source: Aquaculture