Don't Flush him.. that's a horrible way to go. Also, he could live for a while or if it has some disease, it could spread to other life forms, etc. Here is a link on how to euthanize your fish.
:O Don't kill the poor fizzel. Separate him from the others, perhaps his in bad shock, or wounded from the other fish... I say separate him and see how things go for a while!
nah he had lostt an eye , so Chazwick i think its cruel keeping him alive and waiting to see how he goes in the state he was. A peaceful and quick death is what i chose and i feel its the right decsion!