I put it to 82-83 degrees (celcius)...I am a little afraid to go any higher.
Oh, wow, yeah, that's high. I admit I don't know the conversions right off the bat but that seems REALLY high. I wouldn't go above 85 degrees Fahrenheit personally but 90 might be ok.
I would lower it, to be honest. I mean, you'll speed up the life cycle a lot but it's going to put a lot of stress on the fish.