Sexing juvy Convicts?

I think I ended up with two males...mainly because one is half dead hiding by the filter intake, it keeps 'leaning' against it, I can't even get it to eat, it looks pretty bad off. what should I do?!?
 
>.< I don't have a QT tank, I have no idea how to euthanize him. All I have is a gallon bucket I use to transport them around in. How long would they have to stay in the QT tank?
 
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