The ontogeny of courtship, colour and sperm production in male guppies.

The onset of sexual behaviour in three age classes of male guppy Poecilia reticulata occurred in synchrony with the appearance of body colouration and anal fin differentiation but not with sperm production. There was also a positive correlation between sperm production and sexual behaviour in the two older age classes. (C) 2002 The Fisheries Society of the British Isles.