Feeding and reproductive biology of eleotrid fishes in a tropical estuary

Five species of eleotrid fishes (Gobiomorus dormitor, Dormitator maculatus, Eleotris amblyopsis, Eleotris pisonis and Leptophilypnus fluviatilis) are known from the Tortuguero estuary of Costa Rica. One, E. amblyopsis, appears tightly linked to the presence of mats of macrophytes and two others, E. pisonis and D. maculatus, are largely limited to this habitat in the lower estuary. All three of these species feed on hyacinth roots. Despite certain food and habitat specializations among the forms, there is evidence of competition and predation among four species. Individuals of breeding size have never been found in the system for D. maculatus and L. fluviatilis. Alternative means of establishing and maintaining eleotrid populations are suggested.