The blenny family has quite a range of fish and requirements so you'd be better off narrowing down exactly what you want to figure out requirements.
But even the "algae-eating blennies" can often be trained onto other foods. Both my Lawnmower and Starry are pigs when it comes to food. Flakes, pellets, prawn, mussels...and they still pick algae off the glass after all of that. The Lawnmower took a while to figure out there was more to life then algae, but once he did he became quite the fat fish.