Just wondering how long has DE been a problem in silvers? I have just started keeping them again after about 10yrs. I knew of several silvers 30+ inch. and more than 4yrs. old that did not get it. Two of them I raised myself and the others where freinds. Just wondering if people where having this problem 10 or more years ago? And for the record mine beat themselves up on a routine basis and where fed goldfish and mice when big enough to eat them and krill when smaller.