I'm not surprised, the RES I had in my aquarium a few years ago loved eating FHM although 2-1/2" was about the upper limit of what they would eat. They would try to eat longer ones but would spit them out if they couldn't get their mouth closed. The shorter ones they would suck in head first, close thier mouth, then pop thier jaw two or three times crushing the FHM as they swallowed it. I'd see cloulds of small fish scales coming out of thier gill plates every time they popped thier jaw, it was fun to watch. I have a suspicion that small fish are a regular part of thier diet especially after the sun goes down as most of the FHM I fed them disappeared overnight after the lights went out.

Nice pictures!