my pond goldfish are 5"-10+". they eat anyhting that moves and will fit in their mouth in one gulp. mine have never attempted to eat something that they were unable to swallow whole. they have eaten lots of shrimp and and culled fish. I use them for fish that i have to cull, they have eaten hundreds of guppies and convict cichlids that were culled. obviously many WILL chew fish and eat larger fish than what they can simply swallow, but mine do not. when they were babies they had minnows in the pond, but now its just the 5 big goldfish.