Hello! One of my goldfish mysteriously died this morning. She have no visible injury, disease, etc. The only symptom she shows is long stringy poop that I think might be camalanus worm. I dosed the tank with levamisole yesterday and she died today. The temperature for the past 2 days are pretty high. The water hit 79 degree F today. Could that have killed my fish? It is a common goldfish btw. She is kept with a fantail in a 32 gallon tank. There are no ammonia or nitrite and about 10 nitrate. I read that temp close to 80 degree is dangerous to goldfish, but could that have kill them that fast? My other fantail goldfish seems sluggish and listless. I am trying to lower the temp with ice bottles because I don't have a fan or anything. Please help! I don't want my other fish to die too!