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 fry production by female guppy of two commercial strains (lyre tail and red cobra) and (2) to investigate whether dietary L-carnitine supplementation could help in alleviating reproductive problems associated with exposure to temperature stress. For the first goal, females were tested at temperatures ranging from 20°C to 32°C. Temperature was shown to have a significant 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°C. A water temperature of 32°C caused increased female and fry mortality, degeneration of ovaries and reduced brood size. All surviving offspring at this temperature differentiated into males, but suffered from morphological abnormalities. For the second goal, females were tested at the optimal rearing temperature (26°C), and under high-temperature stress (32°C) and low-temperature stress (23°C). The parameters examined were brood size, brood interval and their quotient, and brood size/brood interval, which is the reproduction potential of the fish. Overall, L-carnitine supplementation at a dosage of 1100 mg/kg food, had no significant effect on brood interval or fry production efficiency.