The Seminar comprised lectures by specialists, laboratory work and demonstrations, and practical exercises in induced breeding operations. The major topics covered were:
Role of induced breeding of fish in fish culture development.
Breeding habits of cultivated fishes of the Indo-Pacific Region.
Problems of growth, maturation and fecundity.
Physiological and physico-chemical factors associated with maturation and spawning.
Morphology and physiology of fish pituitary gland.
Techniques of induced spawning without hypophysation.
Techniques of induced spawning by hypophysation.
Techniques of collection, storage and processing of pituitary glands for induced breeding.
Use of synthetic hormones for induced spawning.
Collection, sexing, segregation and holding of spawners.
Hatchery and nursery operations.
Handling and transportation of spawn, hatchlings and fry.
Economics of induced breeding, and organization of large-scale induced breeding programme.
Identification of problems that require further experimental studies.
During field exercises, the participants were grouped into teams, each supervised by an experienced instructor. The principal species of fish used for experiments were:
| Catla | Catla catla |
| Grass carp | Ctenopharyngodon idella |
| Common carp | Cyprinus carpio |
| Silver carp | Hypophthalmichthys molitrix |
| Rohu | Labeo rohita |
Ample time was provided for discussions, and special sessions were devoted to reports by the participants on the induced breeding of fish in their countries, and also for discussions of problems requiring further experimental studies (see Appendix 2).
Each participant was provided with a complete set of lecture notes which had been prepared for the Seminar, and the Proceedings of the FAO World Symposium on Warm-water Pond Fish Culture, Vol.4 (the other volumes were sent to them in their home countries), and a copy of the Synopsis of Biological Data on Catla, Catla catla (Hamilton, 1822) (FAO Fish. Synops., (32) Rev.1).
Thirteen statements, briefly describing fish breeding activities in their respective countries, were presented by the participants. Short summaries of these statements are as follows:
- by Shri G.K. De, Shri K.M. Rao, and Shri M.N. Verma
Since most of the important Indian activities on this subject were covered by lectures and demonstrations at the Seminar, reports by the Indian participants were based mainly on personal experiences.
Shri G.K. De mentioned that high mortality of hatchlings of silver carp had frequently been experienced, but that its cause had not been clearly ascertained. In some cases, smaller hatchlings were produced from smaller eggs.
Shri K.M. Rao described the induced breeding of the Indian major carp 1 by extension workers in Andhra Pradesh, and stated that proper handling and care of the spawners were important factors in the success of induced breeding. The importance of experimental studies on foods and the feeding of spawners was stressed. Intramuscular grafting of mrigal pituitary glands in rohu had produced some successful breeding.
Shri M.N. Verma outlined the salient points regarding activities in induced breeding of the Indian major carp in the State of Madhya Pradesh. In a few cases mature spawners kept along with pituitary-injected specimens, had spawned. Some fish farmers believed that induced-bred fry grew at a slower rate than those collected from natural habitats.
1 Catla (Catla catla), mrigal (Cirrhina mrigala), calbasu (Labeo calbasu) and rohu (Labeo rohita).
- by Mr. Atmadja Hardjamulia
Indonesia has a very extensive fish culture industry in both brackish and fresh waters. The brackish-water ponds cover a total acreage of over 120 000 ha. Chanos chanos is the principal species cultured, the source of supply of fish seed being entirely the natural fry grounds.
Most of the cultured fresh-water fish are able to spawn without hypophysation. Large-scale production of fry and fingerlings, by simple techniques, of Puntius gonionotus, P. orphoides, Cyprinus carpio, Osteochilus hasselti, Helostoma temmincki, Osphronemus goramy and Tilapia has been in continuous operation for a good many years, and many of the Indonesian techniques have been adopted by neighbouring countries. Although hypophysation is unnecessary for spawning these fish, the technique will be of value in experiments in hybridization. It will also be useful in breeding the newly introduced Chinese carp, as well as some indigenous fish under lowland conditions and during off season.
- Mr. Suck Cho Chyung
Common carp, Cyprinus carpio, is the species which has been popularly cultured for many years. A large number of the fry and fingerlings of this species has been produced by government hatcheries for sale to fish farmers and for stocking rivers and reservoirs.
The Pacific salmon (Oncorhynchus) and trout (Salmo) have been propagated artificially on a small scale for many years. Modern hatcheries were established recently and work on salmonids intensified.
Chinese carp were introduced about six years ago. Success in induced breeding by hypophysation of grass carp was achieved in July 1968. Large-scale production of fry and fingerlings of the grass carp and silver carp is now in progress. The techniques used are similar to those popularly practised in Taiwan.
- by Mr. Baharin Bin Kassim
Large-scale production of fry and fingerlings of Cyprinus carpio, Puntius gonionotus, Tilapia mossambica and tilapia hybrids, for distribution to fish farmers and for stocking public waters has been the principal activity of the Fisheries Department's inland fishery stations.
Experiments on induced spawning by hypophysation had been successful on Puntius gonionotus in 1959, on silver carp in 1966, on bighead carp (Aristichthys nobilis) in 1967, but only partially successful on Labeo rohita and Probarbus jullieni. The techniques used were mainly those practised in Taiwan.
Small-scale commercial production of fry and fingerlings of grass carp, silver carp and big-head carp was started by private operators in 1967. The main technical problems encountered had been: (1) difficulties in obtaining fully matured specimens, (2) “plugging” of the genital pore, and (3) high mortality of hatchlings.
- by Mr. Tay Seng Hock
The history of the Tropical Fish Culture Research Institute, Malacca, was described.
Experiments in 1968 on induced breeding by hypophysation of grass carp, silver carp and bighead carp were successful. The pituitary glands used had been obtained from Puntius gonionotus. The quality of the food given to the spawners is believed to have considerable effect on the development and maturity of the gonads.
It was noted that the technique for producing all-male tilapia hybrids - ♂Tilapia honororum × ♀ Tilapia mossambica had already been described during the Seminar.
- by Mr. Krishna Gopal Rajbanshi
The practice of fish culture in Nepal is in an early stage of development, but progress, especially in paddy field fish culture and at private fish farms, is being achieved rapidly through energetic extension services.
Fish culture stations have been established at strategic locations to serve as fry and fingerling production and extension centres.
The construction of a large fish farm (a commercial scale pilot project) is nearly completed, and several large private farms have also been planned for early establishment with government technical assistance and financial support.
The main species of fish now cultured is Cyprinus carpio. Fry and fingerlings of this fish are now being produced on a fairly large scale. The breeding of this carp is induced both with and without hypophysation, depending upon locality and season.
Experiments in the winter of 1967 on induced breeding by hypophysation of the asla or so-called “snow trout” (Oreinus) had been successful.
Chinese and Indian major carp have been introduced into Nepal. Experiments to breed these fish by hypophysation will be started as soon as the spawners are ready.
- by Mrs. M.N. Delmendo
Until 1967, the main fish culture in the Philippines was that of Chanos chanos in brackish-water ponds. At present, about 140 000 ha are in operation for this purpose. Although this fish has been cultured extensively for over 400 years, the supply of the millions of fry needed annually still depends entirely on natural sources. Experiments on induced breeding by hypophysation of this fish have been planned, but unfortunately, mature fish have not been available from ponds or lakes, and the few mature specimens collected from the natural habitat during the spawning season failed to survive long enough for hypophysation.
Fresh-water fish culture is a recent innovation, but its development has been extremely fast. In a span of three years over 6 000 ha of ponds have been developed. The trend is to construct large ponds on idle ground at both upland and lowland (flooded land) areas for fish culture in rotation with agricultural crops. The principal species of fish used are Chinese major carp, Cyprinus carpio, and some indigenous species. Most of the Chinese major carp fry are imported from Taiwan.
Experiments on induced spawning by hypophysation on silver carp and bighead carp were successfully conducted in 1967 and 1968. Two hatcheries are being constructed and commercial production of fry and fingerlings is expected soon. Important problems awaiting solution are: (1) difficulties in getting good mature specimens for spawning purposes; (2) scanty amount of milt from the males, particularly the silver carp; (3) plugging of the genital opening, and (4) high mortality of hatchlings and larvae.
Induced breeding by hypophysation of the local catfish, Clarias batrachus, was successfully achieved in 1966, while attempts to breed the land-locked catfish, Arius, have been interrupted by failure to keep mature specimens alive in ponds.
- by Mr. Zahid Hussain
The first successful attempt to breed mrigal and rohu by hypophysation in West Pakistan was made in 1964, and since then the work has been intensified and extended to cover some other species of indigenous carp.
In West Pakistan, the main difficulties in conducting induced breeding experiments have been: (1) the short rainy season; (2) high water temperature (28°–38°C), and (3) moderate amount of flood. East Pakistan has no such difficulties.
Grass carp and silver carp were introduced into Pakistan from Canton, China, in 1964. It has been reported that male fish have already attained sexual maturity. Breeding of these fish by hypophysation will begin as soon as mature specimens of both sexes are available.
- by Mr. Manu Potaros
The sources of supply of fish seed for the extensive fish culture industry in Thailand are: (a) natural sources: Chanos chanos, Clarias spp., Pangasius spp., Puntius spp., and Trichogaster; from induced breeding in ponds: Clarias batrachus, Cyprinus carpio, Helostoma temmincki, Osphronemus goramy, Puntius gonionotus, Tilapia spp., Trichogaster pectoralis; (c) from breeding by hypophysation: Aristichthys nobilis, Clarias batrachus, Ctenopharyngodon idella, Hypophthalmichthys molitrix, Pangasius sutchi (pangasius), and (d) imported fish, Chinese major carp.
Experiments on induced breeding by hypophysation were first attempted in 1958 but serious attention was not given to this method until 1963. Since then successes have been achieved with: Aristichthys nobilis, Clarias batrachus, Ctenopharyngodon idella, Hypophthalmichthys molitrix, Pangasius sutchi (pangasius), Puntius gonionotus, and P. orphoides.
Experiments on induced spawning of fish are being conducted by both the Department of Agriculture, College of Fisheries, and the Agriculture University. Fry and fingerlings are produced by the government fishery stations and some private hatcheries.
The main problems requiring further experimental studies are: (1) difficulties in getting fully mature specimens suitable for spawning; (2) difficulties in determining the exact stage of ripeness of the ovaries and the degree of readiness for hypophysation; (3) plugging of the genital pore, and (4) high mortality of hatchlings.
The technique for breeding Clarias batrachus in ponds has been described in literature. The important point is to create holes in the banks of the spawning pond below water level to induce the fish to nest and spawn.
The intensive culture of Clarias in small ponds with heavy feeding has also been described. The highest record of annual production was 4 kg/m2 surface area.
- by Mr. Alfred Sin Wai Ching
Hong Kong remains an important nursery and distribution centre of fry and fingerlings of Chinese major carp. 1 The source of supply of the hatchlings and fry used to be entirely from Mainland China, but since 1967 part of it comes from Taiwan.
Success in induced breeding by hypophysation of Chinese carp was first achieved in 1964, but large-scale production has not yet been achieved. The techniques used are similar to those mainly practised in Taiwan. Experimental work will be intensified.
1 Aristichthys nobilis, Ctenopharyngodon idella and Hypophthalmichthys molitrix
- by Mr. Ly-Ke-Huy
Fish culture activities at government stations as well as at private farms have been greatly disrupted by the continuous heavy military operations. However, preparations are now being made by the Government to launch a nation-wide fish culture development scheme at the earliest possible moment.
The principal species cultured are Cyprinus carpio (several varieties), kissing gouramy and Tilapia mossambica. Some indigenous semi-predacious species - Anabas sp. and Clarias spp.- have also been used. All these species can be bred in ponds without hypophysation.
Recently, Chinese major carps have been introduced into the country and preparations made for breeding these fish by hypophysation.
