Effect of temperature-transfer on growth of laboratory populations of a South American annual fish Cynolebias bellottii.

Previous observation had shown that annual fish living at 15 degrees C grow faster and live longer than those at 20 degrees C. We now demonstrate that when populations of these fish undergo reciprocal transfer between these two temperatures, their growth rates change to that of animals living at the temperature into which they have been transferred. These growth rates do not entirely correlate with the longevity patterns observed in annual fish subjected to temperature-transfer, nor to certain other observations of the relationships among growth, temperature and longevity as reported in the literature.