lol no, 90 is too high unless it's a Haitian Cichlid.....86F is good.....86F is perfect for speeding up the life-cycle of Ich and snuff out the hatching eggs w/ salt or medication. 90F is very harsh for a lot of species, especially those that are stressed...................... SUPER-especially for fish that are stressed from unbalanced water conditions., I would not do it. Other than that I agree w/ every post here 99%. Good responses, Fellaz.
Agreed, I was just giving a range because most heaters are a dial/guess/hope setting, unless you're using digital. I think his mollies could handle it but I probably should have just said mid 80s.