While I understand Ch4rlie's position, there are times when one must euthanize a fish for reasons of aggression if all other possible avenues are exhausted. Try the local fish stores, hobbyists in the area (may have a local fish club?). But if those fail and you have no other tanks, temp or whatever, the fish must be destroyed.
An aggressive fish like the CAE can literally weaken and kill every other fish in the tank, so it usually comes down to either the CAE or other fish. Stress from a bully is severe on fish, and weakens their immune systems, and if prolonged, does permanent damage to their physiology.
Not intending blame here, but for the benefit of other readers who may not realize it, this is why some of us caution against this or that species...initially the fish may seem "OK" but this rarely lasts if it is in the fish's nature to be a bully, as it certainly is with the CAE. This is the second thread started today about problem fish, which only shows how real of a problem this can be.
Byron.