Risk assessment of chanchita Cichlasoma dimerus (Heckel, 1840), a newly identified non-native cichlid fish in Florida

Cichlasoma dimerus was only recently discovered in Florida and little is known of its dispersal abilities and potential impacts. Many factors likely contribute to the variability in establishment and spread of non-native fishes in Florida, including biotic (e.g., predation and competition) and abiotic variables (e.g., cold tolerance, low-oxygen tolerance). Of the abiotic variables, cold tolerance is an important regulator of non-native fish geographic ranges in Florida. Its tolerance to cold temperatures is experimentally evaluated and available information on its biology and ecology was synthesized. In the cold-temperature tolerance experiment, temperature was lowered from 24 C by increments of 1 C per hour, mimicking a typical cold weather front. Fish lost equilibrium at a mean temperature of 7.8 C and died at 4.7 C.