lawnmower blenny acting strange

[LifeIsGreat]

I had a starry blenny that did the same thing. It would swim up and down against the glass like an eel whenever it thought I was going to feed it. If I wasn't near the tank it would either perch on a rock or sit in its hole. It did the tail bite thing when it felt some irritation: I noticed a white bump on the tail when the behaviour started.