I had 1.25 inch RES in an aquarium and fed them FH fry. They did eat the smallest fry I put in which were about 3/8 inches long. There was one 1.75 inch RES and it ate the slightly larger fry.
I stocked the first RES into my pond in late March and they averaged 1.25 - 1.5 inches. The FH were spawning at the time and continued to spawn for many weeks. I've been able to observe these stockers very well lately because they're on beds in very shallow water. I estimate they're 3 - 4 inches now.
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The only other fish besides the RES fingerlings and the FH are 24 adult RES stocked from good ol' Mr H's pond this spring. They began spawning about the time the FH spawn slowed down and are still at it. There has pretty much been a constant supply of fry in the pond since the small RES went in.
