Breeding,paternal behavior,and their interruption inBetta splendens

Seven experiments examined the reproductive activities of Siamese fighting fish (Betta splendens). Spawning occurred after heterosexual pairs were together for about 24 h, and males cared for eggs, nest, and fry thereafter. The visual cues provided by an intruder male, but not a female, stimulated aggression in the male breeder, and these agonistic behaviors competed with breeding to cause a decrement in reproductive efficiency. Males were found to protect eggs and fry by preventing the growth of a fungus lethal to their offspring.