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Abstract

Zebrafish is popular aquarium fish and laboratory model species but some aspects of advanced spawning technologies, especially of reproduction and rearing in low temperatures (>25°C), which involve the production of high quality and viable gametes, should be studied. In the present study fish before spawning were reared at cold thermal regime: 19-20°C. From three tested temperatures for fish spawning, the highest spawning effectiveness was noted at 23°C. The highest rate of embryo survival was noted when the temperature in which the spawners were kept before spawning was the lowest (19°C). In the spawning of small breeders groups, the number of males should be higher than the number of females. If the sex rate was 1:1, the lowest embryo survival was noted. From the breeding perspective fish of this species should be reproduced again shortly after the completed spawning a time between spawns should be 20 to 60 days if the spawners were kept at 19°C. Keeping the fish between spawning periods more than 40 days results in a significant deterioration of quality of gametes, expressed as embryo survival. It was observed that spawners of this species produce viable gametes and spawn successfully every 20 days, during a few following spawning periods without changes of embryo survival.