Microspathodon dorsalis is a conspicuous territorial species found in rocky reef systems along the Eastern Pacific whose mating system is not fully understood regarding aspects such as nest distribution, egg predation patterns, and overall reproductive-related behavior. Spatially explicit models indicate that individuals and their nests correlated with substrate structure, principally rocks followed by live Pocillopora spp. corals. Nest size was not related to fish size in the center and along the periphery of the nesting colonies, suggesting that female did not choose males based on size. Up to 11,792 interactions (536 ± 2256.97 interactions/nest) at a rate of 5.95 (± 0.47) interactions/minute were recorded, most of which resulted in unsuccessful predation attempts (63%), while the remaining percent (37%) resulted in successful predation attempts. Thalassoma lucasanum fed heavily on M. dorsalis eggs, followed by Stegastes acapulcoensis and Johnrandallia nigrirostris. The frequency, interaction type, and interacting species varied across space and time, probably due to the spatial location of the nests and the distribution patterns of the interacting species, as well as a consequence of the seasonal environmental variation of the area.