Effects of stocking density on growth, survival rate, reproductive performance and embryogenesis of Zebrafish (Danio rerio)

Abstract

Zebrafish (Danio rerio) has been emerged as a significant model organism over the last twenty years. In spite of having the emerging popularity of the zebrafish model system, the optimal husbandry conditions for this vertebrate are not well defined. The aim of this study was to examine the effect of stocking density on growth, survival rate, reproduction and embryogenesis of zebrafish. An experiment was carried out in five treatment densities (5, 15, 25, 35 and 45 individuals per 2 liter of water) with 3 replica of each. Artificial feed (47% protein) was applied to every tank throughout the treatment period. The duration of the experiment was 84 days. The specific growth rate (%) per day varied from 1.71±0.02 to 0.56±0.02. The highest value came from treatment 1(5 fish) and the lowest one from treatment 5 (45 fish per 2 liter of water). Survival rate (%) varied from 100±0 to 72±16.65. In treatment 1, the highest survival rate observed and the lowest one was observed in treatment 3 (25 fish per 2 liter of water). Reproductive performance was measured in terms of percent spawning success, fertilization rate and hatching rate. The most suitable result came from treatment 1 and the poorest one came from treatment 4 (35 fish per 2 liter of water). The embryogenesis process was estimated in terms of survival rate (%) of embryos at various developmental stages (cleavage, gastrula, segmentation, pharyngula and hatching). An excellent outcome happened for most of the stages in treatment 1, 2 and 3 (no significant difference) and the most unpleasant result happened for treatment 4.