The purpose of an egg tumbler is to allow fresh water to circulate over cichlid eggs that have been separated from the parents. Like other name brand tumblers at a much better price! * A fresh supply of clean water allows the eggs to develop in an oxygen rich environment where mould and fungus development is suppressed without the need for chemicals. * Egg tumblers are used frequently by breeders . * The gentle rolling action caused by these tumblers can simulate the normal incubation of these fish. * Allows egg incubation in same tank as fish are breeding in to provide identical water conditions during incubation period. * Can be used on other non-adhesive fish eggs as well to help prevent fungus. * For instance, tumbling your Cichlid eggs can sometimes be a critical necessity.