The effects of illumination and daily number of collections on fry yields in guppy breeding tanks

Abstract Substantial loss of fry to cannibalism by brood-fish occurs in live-bearing ornamental fish farms. Previous results demonstrated that fry yields in breeding tanks of the guppy fish ( Poecilia reticulata ) can be increased by attracting the newborns by a light stimulus into net baskets from which they are collected. In the present study the effects of the number of daily collections and timing of lighting on fry yield in breeding tanks in the laboratory were tested. No difference in fry yield was found between one and two daily collections, and no effect of the timing of lighting (lighting during the day versus during the night). Contrasting of the morning and afternoon collections within the two-collection treatment under day lighting versus night lighting revealed that more fry were collected when the collection followed the lighting period than the no-lighting period. Experiments conducted in commercial farms revealed no difference in fry yields between one and two daily collections when the baskets were illuminated, concurring with the laboratory results. The farm experiments demonstrated that without illumination there is an advantage for two collections over one collection. Taken together, the results showed that the novel method of using light to attract newborn guppies into mesh baskets have a double benefit; it increases fry yields and concurrently lessens the labor required to harvest maximal fry yields in guppy breeding tanks.