Behavior of the Pupfish, Cyprinodon rubrofluviatilis

Behavior in natural conditions is described for the Red River pupfish, Cyprinodon rubrofluviatilis. Spawning occurred from February into November at temperatures of 13-34 C, with a shift from primarily afternoon spawning in the winter to primarily morning spawning in warmer months. In March, spawning was observed from sunrise until nightfall on days when permissive temperatures prevailed. Maximum spawning frequencies were observed at midmorning hours in July and August. By late October spawning had decreased to a low level. Relative frequencies of different courtship activities were apparently correlated with differential levels of sexual readiness in the female population. Major functions of breeding territoriality seemed to be egg protection and the provision of space in which resident males could court females with minimal interference from