This material is from the 4th edition of The Zebrafish Book. The 5th edition is available in print and within the ZFIN Protocol Wiki.


Suggested Guidelines for Maintaining Mutant stocks

(Source: M. Halpern)


With adequate water flow, stocks are routinely kept at densities of:


To obtain maximal numbers of identified heterozygotes, keep mutant working stocks as intercrosses from identified heterozygous parents. The wild-type progeny from several intercrosses should be pooled to maximize the genetic diversity of the stock. Use identified fish from one generation for experiments, while another generation of intercross progeny are growing towards sexual maturity. On average, make a new generation every 4-6 months.

+/m X +/m
+/+ +/m m/m
1/3 2/3 (die)


To maintain a mutant line, heterozygous fish should also be outcrossed to the wild-type main line. Ideally, the outcross stock should also be derived from group matings rather than a single cross. Identified heterozygous males can be used for freezing sperm.

+/m X +/+
+/m +/+
1/2 1/2

Tank usage

Depending on the use of a given stock, estimate the number of tanks required for stock maintenance, mutant recovery, and experimental purposes:

Category 1: Working stock for maintenance and low level usage

3 X 5 gallon:

4 X 10 gallon:

Category 2: Recovering mutations from clonal fish

Category 3: Major working line

Tanks are needed for

This means at least: 10 X 5 gallon, 5 X 10 gallon and 2 X 30 gallon.

The Zebrafish Book