I noticed that 6 years ago when cleaning off an old buoy sinker. The sulpins would shy away when I approached but the gobys would come in like sharks, within 10" of my mask, and tear the zebras away from the broken pieces of their shells. Real cool to watch close up, I ought to video it.
Last year I thought I saw a rebound in native fishies. The year before VHS, that's viral hemoragic seprosimea or something like that, moved through the area and killed hundreds of thousands of fish. Most of those were reported to be gobys. The source was thought to be the zebras which the gobys ate and the desease would pass up the food chain to seagulls and other things that ate raw fish. I thought that this was the last straw for our fresh water ecology, now I think I was wrong.
Last year we actually started seeing perch minnows again, and lots of bass, and some very large walleye's. I'm guessing that lack of gobys allowed more eggs to hatch. Someone in the DNR said that the walleye and trout are now switching their feeding habits to gobys. Leave it to Mother Nature to come up with a solution to the worst messes we can make, given enough time.