My GC have behaved quite differently than Scott's. 3 summers ago I added 5 GC about 10" long. I was feeding trout at the time. Pond was choked with Elodea.
The GC scarfed pellets and grew like mad. They are now 30". I tried to dissuade them as Scott suggests by catching them on pellets with hook attached. I was able to catch and release only 3 of the 5.
Now, as I have no trout this year, I'm only hand feeding a couple times per week for recreation. The GC come right up close and hoover in the pellets. I can drop a pellet with very small light weight dry fly hook into their midst. They will examine and veer away from that combo. They don't avoid any of the rest of the pellets though.
They certainly have what appears to be great eyesight and are wary of floating fish food with even the smallest of hooks and gossamer line attached.
Here's the good part. Elodea, although still very abundant, is no longer a problem for fishing anymore. The GC have "got with the program" and have opened up 90% of the water so I can
at least cast artificials.
When it is time to remove the carp, I'll shoot 'em.
