Soon after arrival, the aquaculturist checked the broodstock of the Centre. He found only two sexually mature females and several mature males of common carp. Potential broodstock of silver carp were one year less than the age of sexual maturity, and the grass carp stock would be sexually mature only after two years. Due to inadequate manuring of ponds, the potential broodstock of bighead carp grew very slowly. (Appendix 1 gives breakdown by species.)
Partly through the reproduction of common carp breeders of the Centre, and partly through the reproduction of seven young females purchased from local farmers, 500 000 swim-up fry of common carp were produced. The eggs were incubated in Zug jars, which were hand-carried by the consultant. The larvae were kept in hapas after hatching and stocked to nursery ponds at an age of three days.
Artificial reproduction of local species was also attempted. Unfortunately, the mahseer (Tor putitora) due to the unusally early rains in 1984, was past its natural breeding stage at that time. However, the local staff (with the assistance of a fishery inspector experienced in mahseer fishing) will be able to catch breeders and to induce reproduction during the next seasons.
Nursing of common carp was carried out in three ponds, one prepared with artificial fertilizer and another two with organic manure. Food supply was maintained partly through fertilization and partly through the application of organic manure.
The ponds (surface area 0.88 ha) were stocked with a total of 500 000 swim up fry. Though the fish reached the size of nursed fry (400–500 mg) in 12 days, they were harvested only 30 days after stocking, because the objective was to produce small fingerlings, which are more suitable for distribution.
Finally 37 000 common carp fingerlings were harvested, with an average weight of 2.0–3.0 g. The low percentage of survival was due to the presence of large numbers of water insects and insect larvae. At that time the Centre had no suitable insecticide, but later with the use of Flibol (delivered together with the hatchery equipment) much higher survival could be achieved.
After the long nursing period, which produced small fingerlings, only a short period was required for fingerling production. A pond with 0.26 ha water surface was stocked with 26 000 common carp fry with an average weight of 2.0–3.0 g. The fish were fed with rice bran. (Their growth rate is shown in Fig. 1.) The fish were distributed gradually from that pond to the local farmers, 30–60 days after stocking. The rest of the fish was utilized for market fish production at the Centre.
Due to the shortage of sexually matured broodstock, reproduction of grass carp was not possible, but in exchange for 10 000 common carp fingerlings the project received from India 2 500 grass carp fry with an average weight of 1.5 g. The fish were stocked in a pond with a water surface of 0.3 ha. (The growth rate of these fish is shown in Fig. 2.)
An attempt to transport sexually mature Indian major carp breeders from Nepal was unsuccessful; later the project management also failed to organize purchase and transport of swim-up fry of these species from India. Finally 19 000 nursed Indian major carp fry were purchased from India, 10 000 for distribution, 9 000 for fingerling and market-size fish production at the Centre.
After reviewing the possibilities of fish culture at the Centre (water quality, available manure, fertilizer, food, the equipment of the hatchery and the Centre) the aquaculturist prepared the technological plan of the Centre. It contains the most important procedures and basic descriptions of induced breeding, nursing, fingerling and market-size fish production, and summarizes the technology of integrated fish farming (see Appendix 2).
Based on the above technological plan, the aquaculturist drew up the annual workplan of the Centre with a rough estimate of the value of production. The main task of the project would be to sustain the national requirement of fish fingerlings; while, out of season, the facilities (ponds, canals, staff, etc.) could be used to produce market-size fish. Further, occasionally, fingerlings could be exported to north India, which would create a further source of income to the project. Appendix 3 gives current prices of different fish species and sizes and Appendix 4 sets out the annual workplan.
Under the supervision of the aquaculturist, the personnel of the Centre gained experience in induced breeding, nursing, fingerling production and market-size fish production. During the period of artificial reproduction the personnel was trained in:
the selection of broodstock
the method of pituitary gland injection
the proper stripping of eggs, fertilizing and handling with different methods
the incubation of eggs and handling during hatching
handling of larvae and swim-up fry.
During the nursing period the personnel was trained in:
the preparation of ponds, with special respect to manuring and fertilizing
methods of maintaining an adequate plankton population
selection of appropriate time to harvest nursed fry.
During the period of fingerling and market-size fish production the personnel was trained in:
the proper stocking of ponds
methods for feeding the fish
methods of checking of growth.
The local staff was also trained in:
the proper handling of nets
methods for collecting pituitary glands
identification of the most important species of zooplankton
preparing of dragnets.
When the ponds were constructed, an effort was made to cover the dikes with grass. This seems to be the best method to prevent erosion during heavy rains; while at the same time the wet soil of the dikes facilitates high production of grasses even during the dry season, for supplying feed to the grass carp population of the Centre.
After the construction of the broodstock and nursing ponds several banana trees were planted along the fence, and the Fishery Inspector also attempted horticulture activities. His experiments have shown that the following crops could be successfully produced:
ginger
groundnut
eggplant (brinjal)
maize
Tomato and chilli were not successful.
The aquaculturist attempted to culture densely planted maize as this was readily consumed by grass carp. A month after planting it was found that:
planting 30 seeds/m2 gave a production of 2 kg/m2
planting 50 seeds/m2 gave a production of 4 kg/m2
planting 80 seeds/m2 gave a production of 5 kg/m2
With longer growing time the growth rate is far lower and the maize becomes too hard for feeding. It is known that for 1 kg of grass carp production 30–50 kg of green matter is needed; that is, about 10 m2 of densely planted maize can produce 1 kg fish flesh, using the area for one month. (Culture of maize near the drainage canal is possible even during the dry season.)
Given the local technology of paddy culture, the rice fields are not continuously under water, so they are not appropriate for fish culture. The aquaculturist demonstrated the proper construction of a paddy field on a small area which would be suitable for paddy-cum-fish culture.
With the help of Mr Csávás, the FAO Regional Fisheries Officer and the UNDP Office, the aquaculturist ordered various chemical products for the Centre from ARGENT Chemical Laboratories:
for the control of algal bloom; copper sulphate based product
for the poisoning of waste fish in the dugout ponds of local farms, Fintrol and Rotenone were ordered
one inflatable boat with oars and pumps
one fish smoker with accessories
one unit of electric fishing gear with accessories
four small-size fibreglass fish transport tanks with aerators
one diesel generator.
Useful documentation was also ordered. The aquaculturist collected the most important articles of ASFA from 1972 onwards for the Project, the list is attached as Appendix 5.
The aquaculturist requested information from FAO Headquarters, Rome, as to how to order the slides which were prepared for FAO in Hungary by Dr Horváth.
