Genetic variation of fat and glycogen storage in Xiphophorus variatus (pisces; poeciliidae)

1. 1. Individuals from independent sibships of Xiphophorus variatus were maintained at defined feeding levels from birth to sexual maturity, and then killed for analysis of triglycerides and glycogen. 2. 2. Significant variation was observed among sibships in adult sizes, triglyceride and glycogen storage, condition factor and ovary weights. 3. 3. Reduced rations had major effects on growth and energy storage in one sibship ("steep" response), but no noticeable effect in another ("flat" response). 4. 4. Flat and steep responses may be phenotyped in the laboratory and their genetics analysed by reciprocal crosses among lines. 5. 5. Females had higher liver glycogen and lower liver fats than males and appeared to cycle fats between the liver and the ovaries.