Mate choice and size assortative pairing by the cichlid fishes of Lake Jiloá, Nicaragua

Size-assortative mating occurs for all six substratum-spawning cichlids studied in Lake Jiloá, Nicaragua. Mate quality is clearly a dominant consideration for both sexes, as larger pairs had disproportionately more young surviving beyond 3 weeks. Mating with the largest available mate should generally be advantageous to both sexes, since the success of a pair is dependent on their ability to take and defend a territory. A model involving mate discrimination by both partners is developed and contrasted to models involving single sex discrimination with intrasexual competition.