The fish community of the southern Gulf of Mexico is abundant and diverse, and its components are affected by the bycatch of the seabob shrimp fishery. The spatial and temporal abundance and diversity patterns of the fish community are described and analyzed in this paper, and the ecologically dominant species are identified. Monthly sampling was carried out from February 2006 to January 2007, at 37 sites located between the mouth of the Grijalva-Usumacinta system to the mouth of the Chumpan-Balchacah system inside the Terminos Lagoon, in the state of Campeche, southern Gulf of Mexico. Using an experimental trawl net, 444 experimental hauls were done, and 26,386 individuals were caught with a joint weight of 407.1 kg. In total, 94 species were identified, grouped in 65 genera and 38 families. The abundance and diversity of the fish community was analyzed on spatial and temporal scales in terms of density (ind m²), biomass (g m²), average weight (g ind-1), diversity index (H'n), species richness (Dmg), and evenness (J'). The abundance was high in August and September at sites near the mouths of the Grijalva-Usumacinta and Palizada-Del Este systems. The most important species in terms of abundance was the catfish, Cathorops melanopus. The intervals of variation of the diversity range on a spatial scale were H'n = 0.5 to 2.8 bits; Dmg = 2.6 to 5.3 sp ind-1, and J' = 0.1 to 0.8 bits. On a temporal scale, the intervals were: H'n = 1.8 to 2.6 bits; Dmg = 5.1 to 6.7 sp ind-1, and J' = 0.4 to 0.6 bits. Nine dominant species were identified, with 16,840 individuals and a joint weight of 278.5 kg, equivalent to 63.8% of the total capture. [ABSTRACT FROM AUTHOR]