Ornamental Fish Production and Management (1+1)

11.2.3 Guppy

The natural variation in these fish comprised lots of colour and black pigmentation and some extensions of the caudal fin, mostly sex linked inheritance and limited in expression to the males. The principal developments in fancy Guppy breeds include the production of distinctive body colours and very greatly extended caudal fins as in the veiltail Guppy. The body colours red, blue and green seem likely to be derived from the inheritance of simple Mendelian characteristics of autosomal linkage. The black guppy, however, is probably derived by selection of the half-black phenotype due to a gene located in the X chromosome and having a dominant effect in both males and females. The overall genetic control mechanisms are simple, but the combinations are very numerous and the range of strains which have been produced is a tribute to the skill patience of amateur breeders. Further developments seem assured; one special goal should be the separation of the factors determining size of the paired and unpaired fins.