After losing my 2 sens and bowfin i put my Delhezi and Guinean in a cooler while i drain my tank. I had other threads on this issue and i never found out what killed my fish so im going to drain my tank down to the sand. I wanted to know if i will have to wait to put my 2 bichirs in my tank after i drain it and refill it with new water? This may be a dumb question but ive never had something like this happen where i lose this many of my fish so any advice is good.