Novel husbandry practices result in rapid rates of growth and sexual maturation without impacting adult behavior in the blind Mexican cavefish

The development of animal model systems is dependent on the
standardization of husbandry protocols that increase fecundity and reduce
generation time. The blind Mexican tetra, Astyanax mexicanus, is an
emerging genetic vertebrate model for evolution and biomedical research.
Surface and cave populations of A. mexicanus have independently evolved,
providing a model system for studying the genetic basis of divergent
biological traits. While a rapid increase in the use of A. mexicanus has
led to the generation of genetic tools including gene-editing and
transgenesis, a slow and inconsistent growth rate remains a major
limitation to the expanded application of A. mexicanus. The optimization
of husbandry protocols that maximize high-nutrient feed, smaller tank
densities, and larger tank sizes across development, would facilitate
faster growth and expand the use of this model. Here, we describe
standardized husbandry practices that optimize growth through a
high-protein diet, increased feeding, growth sorting of larvae and
juveniles, and tank size transitions based on standard length. These
changes to husbandry had a significant effect on growth rates and
decreased the age of sexual maturity in comparison to our previous
protocols. To determine whether our nutritional change and increased
feeding impacted behavior, we tested fish in exploration and schooling
assays. We found that a change in diet had no effect on the behaviors we
tested, suggesting that increased feeding and rapid growth will not impact
the natural variation in behavioral traits. Taken together, this
standardized husbandry protocol will accelerate the development of A.
mexicanus as a genetic model.