Croatian Journal of Fisheries (Sep 1999)
BREEDING OF ONE YEAR OLD CARP FRY IN VARIED SETTING DENSITY
Abstract
The research was carried out on the fish-farm »Draganići« during the breeding season of the year 1993 (from 19th July to 13th November). In two variants (four exprerimental fish-ponds of 1 ha each) 40 days old carp fry of average individual masa of 0.0009 kg were bred in two setting densities: 30,000 ind. ha -1 (variant I) and 60,000 ind. ha-1 (variant II) in policulture with one month old fry of silver carp (5,000 ind. ha-1 ) and one month old fry of grass carp (10,000 ind. ha-1 ). Throughout the breeding season the research included observations of ecological factors (water chemism, zooplankton quantity, macrozoobenthos quantity) and of ichthyoproduction (yield growth, survival rate of fish, average individual mass of fish, Klark’s condition coefficient, Fulton’s condition coefficient and feeding coefficient). The research results show that all fish-ponds had similar water chemism. Average zooplankton quantity was in variant I 581 ind. l-1 , and in variant II 501 ind. l-1 while the average quantity of macrozoobenthos was 9.49 g m-2 in variant I, and 5.7 g m-2 in variant II. In the carp setting density of 30,000 ind. ha-1 the average survival rate of carp fry was 72.54%, and the average growth of carp was 919.1 kg ha–1 with an average individual mass of 0.044 kg. Klark’s condition coefficient was 3.18±0.02, Fulton’s condidion coefficient was 4.04±0.02 and feeding coefficient was 1.045. With the carp fry setting density of 60,000 ind. ha-1 the survival rate of carp was 66.75%, total growth was 1150.6 kg ha-1 with an average individual mass of 0.0295 kg. Klark’s condition coefficient was 3.32±0.02, Fulton’s condition coefficient was 4.21±0.03 and the feeding coefficient was 1.09. The above presented research results show that in these breeding conditions the setting of carp increased by 100% resulted in a 24.5% greater total growth of carp, but with a 49% smaller individual mass of carp with similar results in other fish farming indicators.
