Do you think DE could be caused by these high strung fish wacking their heads on the covers of the tanks? When mine was young it was extremely timid and could fly around the tank at the drop of a hat. Now it is two feet long and seems to fear very little (except nets, I found out). It has one eye looking downward. Otherwise seems o.k. Real eating machine, likes shrimp (I leave on the shells but remove front and rear spines) and frozen smelt. Sadly shows little interest in prepared foods.