The Reproductive Biology and Spawning of Zebrafish in Laboratory Settings - Zebrafish: Methods for Assessing Drug Safety and Toxicity - page 11

These and other problems related to the loss of genetic diversitymay be alleviated
to a certain extent by careful genetic breeding programs that (1) maximize effective
population size and (2) minimize breeding between siblings or close relatives. Genetic
diversity may also be maintained or enhanced by periodically importing fish from
outside populations and breeding them programmatically with existing stocks.
1.4.4 Behavioral Management
Zebrafish reproductive behavior is complex and undoubtedly exerts myriad effects on
reproductive potential of breeding stocks. The most notable instance of this type of
dynamic involves social interactions between fish in holding tanks. Dominant females
have been shown to suppress egg production in subordinate females via the release of
pheromones (Gerlach, 2006). Further, aggression arising during formation of dom-
inance hierarchies and territory establishment by bothmales and females is a source of
both acute and chronic stress that may also decrease reproductive output (Pottinger
and Pickering, 1992; Fox et al., 1997).
Employing various strategies of behavioral managementmay help tominimize the
potentially negative effects of such interactions on the reproductive capacity of
breeding stocks. For example, the establishment of dominance hierarchies detrimental
to breeding may be prevented to some extent by regularly mixing fish from different
tanks and periodically flushing tanks and systems with fresh water to reduce con-
centrations of repressive pheromones circulating in the water (Adatto et al., 2011). In
addition, maintaining fish at intermediate densities in holding tanks may also reduce
the frequency and intensity of antagonistic interactions, which are highest when
densities are low and territories are easiest to defend (Pickering and Pottinger, 1987).
While an “optimal” density value has not yet been determined for zebrafish, the results
of one recent study suggest that using stocking densities as high as 12 fish per liter has
no negative impact on reproductive performance (Castranova et al., 2011).
1.5 CONCLUSIONS
The impressive reproductive capacity of zebrafish makes them an attractive exper-
imental model for toxicology studies. There are a number of existing tools that are
currently available to breed zebrafish in laboratory settings, and the application of
emerging data on the reproductive biology and behavior of this species will lead to
improved technologies. The efficiency of zebrafish production is dependent upon
sound stock management grounded in key principles of fish husbandry.
REFERENCES
A DATTO I, L AWRENCE C, T HOMPSON M, and Z ON LI (2011). A new system for the rapid collection of large
numbers of developmentally synchronized zebrafish embryos. PLoS One 6(6): e21715.
A LSOP D, M ATSUMOTO J, B ROWN S, and V AN D ER K RAAK G (2008). Retinoid requirements in the reproduction
of zebrafish. Gen Comp Endocrinol 156(1): 51-62.