Effect of temperature and dietary l-carnitine supplementation on reproductive performance of female guppy (Poecilia reticulata)

The goals of this study were (1) to determine the optimal temperature for f ry production by female guppy of two commercial strains (lyre tail and red cobra) and (2) to investigate whether dietary L-carnitine supplementation c ould help in alleviating reproductive problems associated with exposure to temperature stress. For the first goal, females were tested at temperatures ranging from 20 degreesC to 32 degreesC. Temperature was shown to have a s ignificant effect on mean brood interval in both strains, but an effect on brood size was found only in red cobra. Best fry production was achieved at 25-27 degreesC. A water temperature of 32 degreesC caused increased female and fry mortality, degeneration of ovaries and reduced brood size. All sur viving offspring at this temperature differentiated into males, but suffere d from morphological abnormalities. For the second goal, females were teste d at the optimal rearing temperature (26 degreesC), and under high-temperat ure stress (32 degreesC) and low-temperature stress (23 degreesC). The para meters examined were brood size, brood interval and their quotient, and bro od size/brood interval, which is the reproduction potential of the fish. Ov erall, L-carnitine supplementation at a dosage of 1100 mg/kg food, had no s ignificant effect on brood interval or fry production efficiency. (C) 2001 Elsevier Science B.V. All rights reserved.