How long do you think fish could last without a heater? I'm worried... They still don't have my power turned back on and it could be till morning before I get it. Any idea how long they can last? It's supposed to get down in the lower 40s tonight. The tank has already dropped from 78 to 72 and still falling. Since my husband works at an respiratory clinic we got a bottle of oxygen so they won't suffacate so now I'm worried about freezing!