Abstract.Hybridization between tilapia species, to produce all‐male broods, was at one time considered a promising method to prevent uncontrolled reproduction (Hickling 1963). It has been tested with a number of tilapia species, but most attempts at large‐scale hybrid production did not succeed. The major reason for this failure is the instability in production of all‐male hybrids. Sooner or later the system broke down, and females began to appear in increasing proportions among progenies which, up to then, had been all male. It appears that this breakdown is largely due to the infiltration of parental broodstock by individuals of a different genotype, predominantly hybrids between the two species involved, which are difficult to distinguish from their parents. This problem may be solved by a careful examination of the broodstock, often including thousands of individuals, and culling doubtful cases. It requires trained and permanent personnel. Hybridization has been largely superseded by hormonal sex inversion as a method of producing all‐male tilapias. In this paper, the two methods are considered as alternatives, if problems of broodstock purity are solved. Establishing a pilot scheme for hybrid tilapia production is reco
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