I had 4 Florida gar about 10-13 inches had them about 3 and half + years. I went on vacation for a few days but had people check on house so temps stay normal in house. But when I got back one was dead looked stuck behind the filter tube. thought that just sucked. Then the next morning another one died. I use rodi water and nitrate stay about 10-30ppm. I did get 3 of them at same time. I'm doubting its old age but any ideas?