Abstract

MAYA PENA, Eduardo  and  MARANON HERRERA, Samuel. Water temperature effects in sex proportion of Poecilia reticulata Peters, 1859 (Pisces: Poeciliidae). Hidrobiológica [online]. 2001, vol.11, n.2, pp.157-162. ISSN 0188-8897.

Was evaluated the effect of the water temperature on the sex ratio in two populations of Poecilia reticulata, a where it is common practice the inbreeding (native) and another result of a crosses of a imported variety mattered with a local (mestizo). The factorial experiment design (2 × 3) considered both, the populations and the water temperature (21, 25 and 31 ± 1°C). Fifteen juveniles of 2 ± 1 days of age were randomly assigned to each trial with three repetitions, each treatment had 45 fishes (N = 270 cases). During the experimental period survival fluctuated between 91 and 100%. The results indicated that both, temperature and variety of fish species influenced masculinization. The fish male of mestizo population reaches 34.9% at 25 ± 1°C and 63.6% at 31 ± 1°C, while in the native population males were only 3.5 and 2.3% at 25 and 31 ± 1°C, respectively. At the lower temperature of 21 ± 1°C no variation in the sex ratio was observed in the later population and only 4.8% in the former. It was concluded that the highest temperature alters the proportion of sexes, being 31 ± 1°C the one that induced the highest proportion of males in the mestizo population of P. reticulata.

Keywords : Poecilia reticulata; sex ratio; effect of the temperature on sex ratio.