Care and Maintenance of Zebrafish

Care and Maintenance of Zebrafish in Laboratory Settings

In order to use zebrafish as a model organism, the fish need to be kept alive and breeding in colonies large enough for scientists to work with. Below are some key factors in keeping zebrafish colonies alive.

System Maintenance

Zebrafish area best kept in a circulating system that continuously filters and aerates the system water to maintain the water quality required for a healthy aquatic environment. This circulating system also helps to filter excess food and fish excretions. The filters need to be changed occasionally and should be closely watched. The room temperature or the tank temperature is generally maintained between 26-28.5 °C and the lighting conditions are 14:10 hr. The pH of the system water should be maintained between 6.8 and 7.5.

Feeding

Zebrafish can be fed with dry food or live food, though most zebrafish facilities use live food. Brine shrimp eggs are available from pet shops and can be hatched in a laboratory setting. To hatch the eggs are put in a salt water solution, they can tolerate a wide range of salinity. Aerating the water with an air pump and leaving the solution alone for about 48 hours is enough to make them hatch. To collect these shrimp remove the air pipe and allow them to settle for 4-5 minutes, the hatched shrimp will gather at the bottom. These can then be collected to be used as zebrafish food. They can be fed using a dropper or squeeze bottle. The commonly accepted ratio for zebrafish is 4% of body weight in food per day.

Breeding

Zebrafish start breeding at the onset of light. Eggs can be obtained by in-tank breeding or pairwise breeding. Breeding the latter way is best when screening for mutations. For pairwise breeding it is best to set up in the late afternoon, and put the two fish in a breeding tank, or a tank with a bottom that allows eggs to fall through mesh and away from the parents. Embryos can be transferred to a petri dish and either used for experiments or grown up to maintain a colony.

 

 

Raising to Adulthood

Fertilized eggs are kept in an incubator (~28.5 °C) for 72 hr until the larvae are hatched. Once they can swim freely they are ready to be transferred to a main fish tank. Larvae need to be fed from 5 days post-fertilization (dpf) and are kept in embryo medium or system water. To transfer to a tank use a small sized baffle. After 14 days the larvae tanks can be shelved into the system and supplied using the cycling water. Water flow can be increased as the fish grow. It makes about 3 months for the embryos to develop into sexually mature adults.