Lawnmower blenny and 'pod populations

[Delphinus]

Can a lawnmower blenny decimate a 'pod population?

I'm looking into my tank at night last night, and, what strikes me as very odd is that there are no copepods (or decapods, or isopods, or ...) out anymore. This tank used to be white with bugs at night before. Now there are almost absolutely none (I think I counted three, no exaggeration.)

So I jammed some food into the sand (this usually brings them out like nuts). Waited 15 minutes and checked again. Found the nassarius, found the bristle worms, the brittle stars .... but no 'pods. None whatsoever!

On another observation, the lawnmower blenny is big and fat (looks JUST like StirCrazy's picture in the photo section -- an exact replica -- a very large potbelly). He was barely two inches when I bought him, two/three months later he's about 4" or more. (Hard to get a look at him to be sure, he scoots into the rock too quickly, but comparatively to before, he's huge.)

In this case, does 2 plus 2 equal 4? Or should I look for an alternative explanation?

Thanks