Natural history and life history of the Grijalva gambusia Heterophallus milleri Radda, 1987 (Teleostei: Poeciliidae)

We report on basic natural history and life history data of the Grijalva gambusia Heterophallus milleri (Poeciliidae) from a small creek in Tabasco, southern Mexico. Basic biol- ogy of H. milleri is similar to that of other members of the tribe Gambusiini. Insects make up at least part of H. milleri's diet, the tertiary sex ratio was female-skewed, female H. mil- leri produced small offspring, one clutch at a time, relied predominantly on yolk for embryo provisioning (MI: 0.73), and male size was normally distributed.