Title: Techniques of controlling mixed sex tilapia and the practicability of hormonal sex reversal in Cameroon

Tilapia production has grown in recent years leading to the expansion of fisheries industry. Tilapia (Oreochromis niloticus) has the ability to grow fast, to breed in ponds, to adapt to shallow and turbid waters, to resist to diseases and to be flexible for culture and performance in different farming systems. These advantages have encouraged many culturists (small and large scale) to grow tilapia worldwide. However, one of the major drawbacks of fast growth in tilapia is early maturation. This often leads to stunted growth, low yield and unmarketable fish due to different sizes in fish (adults and offspring) competing with the initial stock for food. It has been argued that mono sex male tilapia culture may resolve most of these problems. All males are preferred because they grow faster than the females, they are more uniform in size, and are larger than the females who tend to use more energy for maturing gonads instead of growing. This project reviews mono sex male production techniques including, polyculture, manual sorting, hybridization, hormonal sex reversal, genetic male tilapia and triploidization by heat shock /pressure. Based on this assessment, oral administration of 17 a-methyl testosterone (MT) appeared to be the simplest and most reliable method to produce all male tilapia in hatcheries in Cameroon. This choice was based on the availability of equipment, costs and application of technique. However, as it appears from other studies, treatment of tilapia with MT should be restricted to the first month after first feeding i.e. 25-30 days. Precautionary measures should be taken to avoid direct release of hatchery water into the environment.