Life history of Mexican species of the genus Tlaloc (Cyprinodontiformes, Profundulidae)

Fish of the genus Tlaloc are distributed from southern Mexico to Central America and are a distinctive example of the endemic fauna of the Mesoamerican highlands, which has been scarcely studied in Mexico. The present study provides basic life-history data for the species Tlaloc hildebrandi, T. candalarius, and T. labialis, which are native to the headwaters of the Grijalva-Usumacinta basin in southeastern Mexico. We collected 918 specimens to determine their Length-Weight Relationship (LWR), Relative Condition Factor (Kr), sex ratio, Gonadosomatic Index (GSI), fecundity, and size at first sexual maturity. Both sexes of all species had positive allometric growth, except for T. candalarius females (isometric). Mean Kr and sex ratio values differed significantly among species. Females’ GSI values differed significantly among species but were highest during the dry season in all three species. Absolute fecundity was positively correlated with standard length and weight. Sexual maturity was reached at different lengths among species. Based on these results, we suggest that all three species present an opportunistic life strategy, which is very common in fish of the order Cyprinodontiformes. These results represent a first contribution on the life-history of this group of fish and provide basic information that is fundamental to ensuring their conservation.