Abstract:
Indonesia is a producer of ornamental fish and one of the commodities that has its own charm for its consumers, such as zebrafish (Danio rerio). The zebrafish has a four-stage life cycle: embryo, larva, young fish and adult fish. Zebrafish have the advantage of producing 300-400 eggs/week, transparent embryos so that their organs can be observed clearly, and easy to maintain. Egg quality is a primary factor in the success of fish hatchery. Quality eggs have high fertilization and hatching rates. This study aims to analyze the factors that can affect the process of embryo development and hatching of zebrafish (Danio rerio) eggs. This research is a mixed type of descriptive experimental and quantitative explaining all stages of development and the ratio of egg hatching and embryo development. The results of the study found that natural feeding was able to accelerate growth, ward off disease germs, and accelerate gonadal maturation. The best time to release the broodstock is in the morning and evening because the water temperature tends to be low. The results of observing eggs under a microscope found an attack by the fungus Saprolegnia sp., this fungus tends to grow spread on the surface of the egg and forms hyphae. Larvae hatch from 48 hours to 72 hours after fertilization. The 2-3 dpf larvae are kept in the hatching medium until they become seeds. The safety rate for embryos is around 50%, while for larvae up to 21 dpf it is around 100%. This is caused by the fungus Saprolegnia sp., so that the index value of the hatching ratio is less than optimal due to retarded embryo growth and leads to death. However, the high survival rate is due to optimal management of larvae rearing by providing proper feeding of dancow milk powder and good water treatment.
