To analyze the fish community in La Cruz coastal lagoon, Gulf of California, samplings were carried out during 1989-1991 with four types of fishing gear: plankton net, beach seine, cast net and otter trawl. A total of 34 families, 63 genera and 96 species were registered. The otter trawl caught the highest number of species (48), followed by the plankton net (40), beach seine (37) and cast net (28). The most representative species for each gear, according to the biological value index, were: juveniles of Leuresthes sardina for beach seine, and juveniles and adults of Urolophus maculatus for the cast net and otter trawl. The families Gobiidae, Atherinidae, Gerreidae and Engraulidae were important at the larval stage and responsible for the minimum diversity values. Representatives of these families were also important at the juvenile stage. Thus, changes in diversity were influenced by the succession of dominant species. Species of Urolophidae and Gobiidae were found in different development stages, which indicates that they have high dependency on the system for their vital cycle. It is suggested that La Cruz lagoon is an important area for many fish species that make extensive use of it as a refuge, nourishment and/or reproduction zone.