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A guide to raising baby zebrafish

Raising zebrafish to adulthood can be challenging. Here are some steps to prevent high mortality rates.

Equipment:
Baby Rearing Tanks
Small Mating Tanks or Petri Dishes
Liquid Fry and Paramecium
Water Filtration System
Water Purification Chemicals

Procedure:

0-7 days post-fertilization
Zebrafish embryos should be raised for the first seven days in a shallow container (for example a petri dish or crossing tank). Do not feed the embryos/larva during this stage. They do not need food as they are still getting all of their nutrients from the yolk, and the added food will cause the water quality to decline and promote the growth of contaminants. When the larvae get their swim bladders, they are ready to be switched into a larger tank. Note that if the babies get put into a large/deep tank too early, they may have trouble obtaining the air they need to inflate their swim bladder.

7-14 days post-fertilization
If your aquatic system has recirculating water, adjust the water to very slow drips until the larva are about 3 weeks old. If you are rearing the zebrafish in regular fish tanks, turn off the filter and do a 5% water change each day.

Finding a food that gives excellent survival of the larva during the first few weeks they are in a large tank can be challenging, and may take some experimentation. We have observed that zebrafish at all stages do better if their food floats at the air/water interface at the top of the tank. Here are some ideas:
1. Live paramecium (traditional and widely used food for baby zebrafish) downside-paramecium cultures can crash and/or become contaminated with other organisms that harm the fish-thus it is imperative to carefully monitor the quality of the paramecium cultures.
2. Liquid fry-we have stopped using this because it does not float, and it makes a horrible smelly mess on the bottom of the tank that seems to kill the small larvae
3. Our recent favorite: green powdered food that is composed of equal parts spirulina (dried algae) and Argent Chemical Laboratories Hatchfry Encapsulon Grade 0 (Aquac. Res. 37, 1107-1111).

2 weeks-2 months
In about two weeks, the fish will have grown and will be able to eat larger pieces of food. The diet can now changed to flake food that has been ground into very small pieces and hatched brine shrimp. After one to two months, the fish will be big to eat a regular adult diet (for example, brine shrimp and flake food).