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The best age for broodstock of various species is not defined, but as a general rule the size of animals capable of breeding corresponds to the size at which onset of maturation occurs in the wild for a given species. Because size of a poikilotherm at a given age is extremely dependent on culture temperature, as well as adequate nutrition, age alone is not a good predictor of breeding readiness. In nature, as well as in ponds, attainment of potential for sexual maturity and breeding usually occurs in 8 to 10 months. A simple indicator of breeding readiness is appearance of ovarian development in some females in a population. Sexual dimorphism for size is generally exhibited in mature Penaeus sp., with females being larger than males. Broodstock cultured in captivity, especially males, sometimes appear to require a larger size than size at first maturity in the wild to be reproductively viable (Bray & Lawrence, 1992).
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