Resumen en inglés: "With the purpose of characterizing the ichthyoplankton assemblage and its distribution across the coral reef off Mahahual, Mexico (western Caribbean), a short-term and small scale survey was conducted. Plankton samples were sampled during the day and night over 4 d (30 December 1990 to 2 January 1991) in three reef zones: fore-reef, channel and reef-lagoon. Highest egg densities occurred in the fore-reef zone at night. Highest larval densities occurred in the reef-lagoon zone and were significantly greater at night. Thirty species, 54 genera, and 73 different taxa belonging to 54 fish families were enumerated. The most abundant families collected were Tripterygiidae (31.8%), Gobiidae (26.5%) and Clupeidae (6.0%). Although sampling occurred during aggregations of Nassau grouper, Epinephelus striatus, no E. striatus larvae were collected. Ecological analysis included 44 families with relative abundance ≥ 0.1%. Richness, expressed as the number of families, and diversity were higher in the fore-reef. Jackknifed values of Shannon-Wiener diversity index were statistically greater at the fore-reef zone than in the reef-lagoon. Multivariate classification analysis by reef zones grouped the fore-reef and channel zones together. Clustering by families revealed two groups. One group included the most abundant families in the reef-lagoon and channel zones, and the other the oceanic families, some of which occurred only in the fore-reef zone. It is concluded that prevailing hydrographic conditions in the area might be an important factor in determining the composition and distribution of fish larval assemblages found over Mahahual reef. "