The Reproductive Biology and Spawning of Zebrafish in Laboratory Settings - Zebrafish: Methods for Assessing Drug Safety and Toxicity - page 9

a range of habitat types that vary considerably in their physicochemical properties as a
result of local geology and pronounced seasonal fluctuations in rainfall patterns
(Talwar and Jhingran, 1991). However, it should be recognized that there is an
energetic cost to fish in operating outside their optimum range of environmental
parameters. Animals maintained under suboptimal conditions must devote an in-
creasing proportion of energy towardmaintaining homeostasis, rather than on growth,
reproduction, and immune function (Wooton, 1998). Consequently, one major
consequence of fish being held under suboptimal conditions is a decrease in the
number and quality of offspring (Haywood, 1993). Thus, it is vital to manage water
chemistry as close to optimal as possible to ensure that fish allocate resources to
reproductive function.
Stability within a given range of each parameter is also crucial, and may be more
important than maintaining at optimum, especially for a generalist species like
zebrafish. Adapting to constantly fluctuating environmental conditions is energy
intensive, and can be a source of chronic stress that manifests itself in decreases in
number and quality of offspring (Wooton, 1998; Conte, 2004).
While managing water quality for stability within optimum ranges is straight-
forward conceptually, it is a bit more challenging to achieve in practice, primarily
because optimum environmental conditions for zebrafish for the most part have yet to
be demonstrated experimentally. Until such data are available, the soundest practice is
to base management on the best available scientific information. Observational data
fromyears of experimental use alongwith concepts gleaned frombiological studies of
zebrafish allow for a reasonable place to start, however. Adetailed treatment of each of
these factors relative to the management of zebrafish is given in the review by
Lawrence (2007).
1.4.2 Nutrition and Feeding
Nutrition and feeding are among the most important determinants of reproductive
success—or failure—in zebrafish facilities. Therefore, to ensure efficient and sci-
entifically sound management of breeding stocks, it is essential that managers and
technicians possess a thorough understanding of fish nutrition and the different types
of feeds available, as well as the techniques to deliver them.
While the specific nutritional requirements of zebrafish are yet to be determined,
it possible to apply scientific principles of finfish nutrition, along with what zebrafish
specific data does exist in the design of diets and feeding regimens that will support
high levels of production. At the most general level, stocks should be fed balanced
diets with adequate levels of essential nutrients: proteins, lipids, carbohydrates,
vitamins, and minerals. Deficiencies in essential nutrients will result in reduced
production, low growth, and decreased immune function, among other problems.
At minimum, it is also crucial to ensure that diets used for breeding populations of
zebrafish contain adequate levels of specific nutrients known to support reproductive
function in fish. Most notably, these include the highly unsaturated fatty acids
(HUFAs) eicosapentaenoic acid (20:5 n -3; EPA), docosahexaenoic acid (22:6 n -3;