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



(Source: M. Westerfield)

Several different types of water are used for procedures described in the following sections. These solutions have been adapted to balance ease and cost of production with the changing needs of zebrafish during their life cycle.

In general, adults can be maintained in tap water, conditioned by letting it set. This depends critically on the quality of the local water source and on the demands for embryo production. Poor water quality will adversely affect the health of the fish, their susceptibility to disease, and their breeding potential. If there is any question about water quality, deionized or distilled water should be used to which a small amount of salts and minerals are added. If an adequate supply of deionized water is unavailable, a closed-system which recirculates the water after purification can be used.

Embryos and young larvae have stricter requirements and should be raised in egg water. Embryos removed from their chorions require additional calcium and should be maintained in embryo medium.

System (or tank) water: water out of the facility's water system. This water is dripped into clean tanks and is used for setting up pairwise crosses.

Egg water: Used for in vitro fertilization and raising young embryos.

Stock salts: 40 g "Instant Ocean" Sea Salts added to 1 L distilled water
Egg water = 1.5 ml stock salts added to 1 L distilled water = 60 µg/ml final concentration.
Embryo medium: Don't confuse with "egg water" above. Used in handling dechorionated embryos and storing young embryos in dishes. This is basically 10% Hank's with full strength calcium and magnesium. Embryo medium
1.0 ml Hank's Stock #1
0.1 ml Hank's Stock #2
1.0 ml Hank's Stock #4
95.9 ml dd H2O
1.0 ml Hank's Stock #5
1.0 ml fresh Hank's Stock #6
Use about 10 drops 1 M NaOH to Ph 7.2
Hank's solutions: Hank's solutions can be made from stock solutions (kept refrigerated, they will last for several months). A premix of the salts can be stored in the refrigerator for several weeks. Sodium bicarbonate does not store well, so it is made up fresh each time Hank's solution is made. Full Strength Hank's
0.137 M NaCl
5.4 mM KCl
0.25 mM Na2H PO4
0.44 mM KH2 PO4
1.3 mM CaCl2
1.0 mM Mg SO4
4.2 mM NaH CO3

Hank's Stock Solutions
Stock #1
8.0 g NaCl
0.4 g KCl
in 100 ml ddH2O

Stock #2
0.358 g Na2HPO4 Anhydrous
0.60 g KH2PO4
in 100 ml ddH2O

Stock #4
0.72 g CaCl2
in 50 ml H2O

Stock #5
1.23 g MgSO4-7H2O
in 50 ml ddH2O

Stock #6