I think my fish suffocated. I think it was a matter of too many fish with ICH (less effective gill function) in a small tank with insufficient aeration. I'm inclined to think this because the blenny was breathing rapidly when I found the other fish dead. I added a Maxi-Jet and opened the air valve most of the way then went to work. When I got home, the blenny was breathing normally. Also, the dead fish had their gills splayed out like they weren't getting enough oxygen.