Bi-color Blenny is eating coral?

Having heard of problems with bi-color blennies eating coral and yet enjoying the personality of the fish, I bought one to see how it would fare in my 10 gallon reef in the window.

It immediately took up residence in the burrowing sponge hole in one of the two pieces of purchased live rock. It wiggled and scooped until the hole was emptied of debris. (debris that I thought would have dropped out when I turned and shook the rock underwater as I always do to live rock to get the air out).

If you don't know about burrowing sponge, it's the organism that creates much of the internal porosity of the live rock we buy. Unfortunately it usually dies in transit so we don't get to enjoy the benefits in our aquaria. One of those benefits, I believe, is to release calcium carbonate in solution as it creates it's burrow.

Anyway, back to the blenny. It eats ravenously. It eats brine shrimp and flake food. It also eats the thin slimy coating of algae that grows so well over live rock each day.

Here is the point of interest. The blenny has taken quite a few chomps of the new growth of flesh of my large acropora cutting that I set on top of a rock without glue. The end where the acro broke had stated to be covered with flesh and is smoother than the sharp polyps of the rest of the acro. It is continuing to chomp as the acro continues to gow over the end. Joe and Cindy Jones (long time hobbyists and club leaders) have seen a Bi-color blenny eat green star polyps until they removed it!

Here is my theory: This blenny is omnivorous so when it finds that it's only source of soft algae is in the coral, that's what it eats. And further, my theory is that we all tend to discourage algal growth while trying to succesfully keep organisms that cannot thrive without it and it's communal inhabitants.