Ontogenetic feeding shifts, diel feeding and differential feeding between sexes in the molly miller, Scartella cristata (Family Blenniidae), were characterized by dietary analysis. Gut-content analysis was performed on juvenile and adult S. cristata (n = 62) based on 24-h collections from two rock jetties in northwestern Florida. Direct observation suggested that sexes have different activity regimes; males were encountered more frequently during day collections while females were encountered more frequently during night collections. S. cristata was observed biting algal turf, and its diet consisted of algae and associated invertebrates with a lesser contribution from benthic and demersal invertebrates. An ontogenetic shift from predation on demersal and benthic invertebrates among juveniles to a fuller exploitation of the algal turf as adults was observed. ANOVA was employed to examine the influence of site, sex and time of collection on total gut-content biomass (including algae) and total invertebrate prey biomass. Although there was no site effect in total biomass comparisons, differences between sampling sites contributed significantly to variation in male and female total invertebrate biomass suggesting that local abundance of invertebrates may influence feeding by S. cristata. Although no differences in total gut-content biomass among females collected during the day and night were detected, females contained a significantly higher invertebrate biomass during the night than during the day due to foraging on demersal invertebrates. During the day, males and females ingested similar invertebrate prey taxa, and total gut-content biomass estimates and total invertebrate biomass did not differ in males and females. Males were observed to actively nest guard clutches of eggs and this behavior may have lead to a reduced activity regime thereby decreasing male foraging on demersal invertebrates.