PROCESS FOR INCREASING THE BODY SIZE IN MALES OF GUPPY (POECILIA RETICULATA) ORNAMENTAL FISH SPECIES

摘要

The invention relates to a process for increasing the body size in males of guppy (Poecilia reticulata) ornamental fish species, by using estradiol valerate as feminizing hormone. The lots of plump males of Poecilia reticulata species, obtained by the claimed process have body sizes exceeding by 20...40% the body sizes of non-hormone treated witness lots; within the first 2...3 months of life they have a macroscopic morphologic development similar to females, and the moment of sexual differentiation, more precisely the intense colouring, the formation of the gonopodium and courtship behaviour may be decided by the breeder, the last three ones being manifested in treated males within about 8...20 days from the end of the hormonal treatment; irrespective of this variety or lineage, they begin the sexual differentiation at late ontogenetic ages, namely at 2.5...3.5 months, allowing the development of the posterior half of the body and of a robust caudal peduncle, specific to females, by 30...40% thicker than the caudal peduncle in non-hormone treated lots.