Keith,

I think it's probably an injury at some point that caused his gill to heal that way. I did have some brook trout that had gill covers permanently fused open but that is probably different. That was due to gill infections due to to much silt in the water (excavator came later in the year and I was never able to grow sufficient vegatation to keep erosion down).

As far as the ones in the aquarium shorter and fatter it's most like due to excess feeding or what you are feeding them.

If pigs could fly bacon would be harder to come by and there would be a lot of damaged trees.