"Native to the reefs of Java, the Black Sailfin Blenny requires ample live rock with microalgae growth on which it can forage for food. This member of the Blenniidae family is an obligate microalgae eater, which means it needs microalgae in its diet in order to survive. However, its diet can be supplemented with vegetable matter, including frozen and dried foods containing marine and blue-green algae (spirulina)."
this indicates that it will pick at algae, therefor not sift sand