Lawnmower Blenny (Salarias fasciatus)

The Lawnmower Blenny — also sold as the algae blenny — carries a set of comb-like teeth built for one job: scraping filamentous algae straight off rock and glass, which makes it one of the few fish in the hobby you're actively rooting for to eat your tank instead of your food. That specialization is also the catch — a tank kept too spotless can leave one thin, so don't be surprised if yours starts eyeing frozen mysis and herbivore pellets as a backup plan.

Care level: Easy · Temperament: Peaceful · Max size: ~5" · Min tank: 30 gal, established algae growth · Diet: Herbivore, algae + herbivore pellets