Enligt http://www.tfhmagazine.com/details/articles/ber-algae-eaters-the-lawnmower-blennies-full-article.htm äter de allt möjligt, främst detritus. Det här låter nästan som en sandvändare på beskrivningen:
While they do eat some algae (the amount varies from one species to the next), recent studies have shown their primary source of food is detritus in the form of detrital aggregates. Because detritus is often overlooked in food-habit studies, its importance as Salarias food has long been overlooked.
These blennies scrape this material off hard surfaces (e.g., coral rock, dead coral skeletons), along with some algae. They will also incidentally ingest tiny invertebrates. For example, the diet of S. fasciatus has been reported to include filamentous algae, diatoms, foraminiferans (shelled protozoa), tiny crustaceans, detritus, and sand. On occasion, this species will also consume fish eggs, sponges, and small snails. They ingest a significant amount of calcium carbonate as they feed, which is not uncommon for herbivores with less selective feeding tactics. While many of the Salarias spp. eat some algae, some steer away from the filamentous forms that can overgrow our aquariums. For example, S. patzneri selectively feeds on smaller particles less than 125 mm [sic] in size (mainly detritus) and avoids those in excess of 250 mm [sic] (that is, algal filaments).
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Individuals vary in their usefulness in controlling some of the dreaded hair algae species. Some of the larger species (e.g., S. fasciatus) regularly consume filamentous algae. However, there are individual Salarias that tend to ignore it, choosing instead to rasp diatoms and other unicellular microalgae off the aquarium glass or live rock. It has been suggested that if you frequently feed them other foods, they will be more reluctant to dine on the dreaded hair algae.