Common carp (Cyprinus carpio) breeding has a long tradition in Hungary. However, recent economic changes in Eastern Europe and new developments in aquaculture necessitated the need for ensuring quality of the brood stock used in hatcheries and the legal and institutional frameworks needed to implement the program. In addition to good research and development programs and gene banking, it became essential to establish an appropriate legal framework, organize, coordinate and control breeding activities, and provide financial support.
The background to the setting up of the project is summarized and an outline of the project given. The 4 tilapiaspecies currently available are Sarotherodon mossambicus, S. niloticus, S. aureus and Tilapia zillii . The progress made so far is described briefly.
The reproductive potential of three tilapias (Oreochromis aureus, O. spilurus and a red tilapia from Taiwan) were tested in 2 m3 fiberglass tanks with a water salinity of 3-5 ppt. Also, the hybridization of O. spilurus and O. aureus was attempted. The tests lasted for 192-207 days. Eggs were collected weekly and incubated artificially. The number of fry produced was noted. Results showed O. spilurus to have the highest reproductive potential based on fry production (75 fry/m2/day) adn the longest spawning season.
The commercial success of a giant freshwater prawn (Macrobrachium rosenbergii) hatchery depends upon the uninterrupted supply of the desired quantity and quality of broodstock. This study was an attempt to develop the broodstock near a hatchery, to be used for seed production throughout the year. The hatchery produced seed were stocked at the rate of 3/m2 after initial pond preparation. The prawns were fed with a pelleted diet (3 mm size) prepared by using locally available feed ingredients.
Optimal sex ratio in tilapia breeding ponds depends upon stocking density. However, under certain circumstances, altering the male: female sex ratio from a more or less natural 1:1 to 1:2 or even higher has been shown to increase fry production in oreochromiines. The research reported here was a first step toward establishing the broodfish sex ratio that Malawian smallholders ought to use to produce the maximum number of 0. shiranus fry under local conditions.