A novel technique for mass induction of propagation in small fish species: Hormone immersion.

Due to the lack of environmental stimuli found in their natural habitat, not all species of tiny fish can reproduce naturally in the conditions of captivity. Silver rasbora (Rasbora argyrotaenia) was used as the model organism in this study, which is the first to successfully use the hormonal technique of immersion to mass induce spawning and spermiation in small fish species. In this study, in order to find out the effect of immersion hormone treatment, two separate experiments in which commercial hormone Ovaprim™ was used for spawning induction and Ovagold™ for spermiation induction were conducted. Four doses of hormones (0.0 mL/L, 0.7 mL/L, 1.4 mL/L, and 2.1 mL/L) were evaluated on 24 females and 40 males in total. According to the experimental findings of female breeders, 1.4 mL/L dose of Ovaprim™ showed best results on latency period (8.67 h) with a total number of eggs (6994 egg) and fertilization rate (99.22 %). In addition, hatching and larval survival rate have also increased. Milt volume and sperm concentration have also seen an increase to 4.25 μL/g bw and 42.71 106 cell/μL respectively at 2.1 mL/L hormone concentration. The best results or responses were obtained by immersion treatments using Ovaprim™ doses of 1.4 mL/L on female and Ovagold™ concentrations of 2.1 mL/L on male. This new technique is a beneficial for breeding small fish species for either commercial or conservational culture condition.