Artificial zebrafish (Danio rerio, HAMİLTON 1822) breeding and sex ratio under controlled laboratory condition

Zebrafish are considered as model organism and widely used in biomedical research to study human genes and human diseases. Despite this, the artificial reproduction of zebrafish is poorly described and there is not any standard universally accepted artificial culture protocol. In order to satisfy the scientist working in biomedical area, a standard culture method of zebrafish under controlled laboratory conditions must be developed. This thesis investigates artificial culture of zebrafish in the laboratory where culture conditions were maintained. In addition, embryogenesis, egg diameter, sex ratio were investigated. Mean body lengths for female and male were 3.34±0.40; 2.97±0.3cm and the mean weights were 0.38±0.14; 0.25±0.27g, respectively. Spawn traps and gravels are not used for spawning of broodstock. The maturation stage for both male and females was detected at 90 days after hatching. Female and male broodstock were selected from our previously cultured stock, based on their swollen abdomens. First eggs were squeezed from the ovaries then milt was taken from the testes onto the eggs. Fertilization was done artificially by the dry method. The eggs hatched within 4-5 days at 28±1ºC. The mean diameter of eggs and fecundity were measured. Mainly seven developmental stages of embryogenesis were described; the zygote, cleavage, blastula, gastrula, segmentation, pharyngula and hatching stages. The sex ratio of the 163 sampled fish was 109:54 (male: female) and this difference was significant (p< 0.05). Additionally, final live mean weight of the females was higher than that of the males (p>0.05). The results of the present study suggests that sex ratio were male biased and with the right artificial culture conditions and proper manual stripping, the required number of eggs and embryos for biomedical research can be easily obtained.