The effect of cyclopropenoids on lipid metabolism in rainbow trout (Salmo gairdneri), with emphasis on the incorporation of fatty acids into both neutral and phospholipids will be investigated. Comparisons will be made between activity found in trout and that in warm blooded species such as the rat and mouse. The investigation of the cocarcinogenic effects of cyclopropenoids in mice will continue, and results will be compared with those in trout experiments.