 For example, the aptly named Lawnmower Blenny will keep your green algae well trimmed and presentable.With the exception of Fang Blennies, Blennies are totally reef safe- in fact a reef environment is really best for them because they can be shy and the intricate rockwork of a reef provides ample hiding spaces.They are omnivores and should be fed a varied diet of frozen or live foods and plant matter.