I don't think he can make it another day, in fact I'm not sure that he isn't too far gone already. Even floating a bowl in the tank with him in it would be preferable to the current situation. I have never seen a rainbow in such bad shape.they were doing fine until a week ago when the cichlids took notice to them. i had them in a different tank for years with no problems. he will be removed in a day or 2.