This material is from the 4th edition of The Zebrafish Book. The 5th edition is available in print and within the ZFIN Protocol Wiki.
GENERAL METHODS FOR ZEBRAFISH CARE
Availability and simple care
Zebrafish are available at pet stores throughout the world. They can be most easily maintained in 10 gallon (45 liter) aquaria heated to 28.5C (above 31C and below 25C, zebrafish probably won't breed and development will be abnormal) with 25 fish per tank. If you replace 1/3 of the water each day by siphoning up debris from the bottom of the tank, a separate tank filtering system will not be necessary. Otherwise use a filter and replace about half the water at least once a week. Tap water, aged a day or more in an open (heated) tank to release chlorine, is adequate although more consistent conditions may be obtained by adding commercial sea salts to deionized or distilled water (60 mg of Instant Ocean per liter of water, for example). Adults should be fed 1-2 times per day with a variety of food (see below). It is a good idea to clean the tank by siphoning after the second feeding.
The Zebrafish Book