Ovaries were cryoprotected in 30% sucrose overnight and then in ascending OCT (Tissue-Tek)/sucrose solutions for 3 days before embedding in 100% OCT and stored at 80 C for two to six weeks until sectioning. Ovaries were sectioned at 16 lm, mounted onto gelatin-coated slides (Superfrost/ Plus; Fischer Scientific), and stained with hematoxylin and eosin for histological analysis. Reproductive state was determined based on an oocyte maturation staging protocol developed for another cichlid fish, the redbelly tilapia Tilapia zillii [13].