Did you take a look at his liver by any chance? (But if the fish was dead for some time before you showed up this wouldn't work) If so, was it pale? Also did he have a good amount of fat reserves in his body? My concern is overfeeding in cool water could cause liver problems. That is, they could become functional diabetics according to Dr. Paul Brown a fish nutrition biologist of Purdue. These kinds of fish will grow fast, look very robust, but may not handle stress as well as a fish that does not have this condition.
I was told by Mike Robinson of Keystone Hatcheries the same thing, that is, to stop feeding bass and bluegills below 50 F. as the fish will cotinue to eat out of reflex, but they have a hard time metabolizing the food.
I still say you could be selectivly breeding for aggressive hard feeding fish which in itself is not bad, but they could be more prone to overeating in cold water.
Just my thoughts and passing on what I have heard from these two gentlemen. Of course I could be overstating it.
If anyone would like to contact Dr. Paul Brown of Purdue I have his email. In fact maybe Bob Lusk would as the next issue is concentrating on feed issues?
I did look at his liver and it was slightly light colored, but I'm not knowledgable enough to make and assumptions based on what I saw.
The fish had an insane amount of fat reserves.
My water never drops below 50 degrees in the winter, so I'm probably OK with the heavy duty feeding program.
I was unable to identify any parasite in the fish.
I don't think we'll ever know if we're selecting for rapid growth or agressiveness. Common sense would dictact that it's probably some combination of each. It would take a controlled study of some kind to tell--probably where you would have two identical tanks, some standard BG and some CSBG and feed them exactly the same and see what happens. All I really know is that it is accomplishing my goal, which is getting to 3/4 pound really fast! Since I've seen several fish from the F-2's at over 1.5 pounds I think that you can assume that the long term fitness is probably OK.
I think you're exactly right in your comments regarding health problems with fish that eat exclusively pellets, but because my fish were released into a sizable pond last summer, and I feed fatheads and krill all winter that over 50% of my total BG calorie intake comes from natural sources. I think this will be ultimately helpful.
Holding a redear sunfish is like running with scissors.
