we actually did a very extensive fish "exercise" experiment with lake trout over the first half of this year. some fish were held in high flow active swimming tanks, others were held in low flow minimal swimming tanks. energetically, there was statistically no differences between the two groups. we are still looking at other issues like lipid content, etc. that being said, this experiment suggests to us (and we controlled for quite a bit) that exercise was not really an issue with the fish.
what i would extrapolate to this situation is that it's not exercise that is leading to the fat buildup in captive gars, it's likely the food content itself and the amount of food they are getting. exercise may play a role between wild and captive fishes, but our pretty well-developed experiments did not support this. there are other factors at play. what i do know is that we rarely see fat bodies (or nearly the amount of fat bodies) in wild gars as we see in captive gars.
in general, captive gars are often overfed IMO. i feed pretty minimally with my adults (1x a week, probably bumping up to 2x this summer), and they look healthy and have no problems per se. hopefully we'll be able to further elucidate the details of this issue in the future--
--solomon
