Right now I have 3 rbp's in a 40 gallon, 2 of them are 4" and one of them is 3.5". I will be upgrading to a 75 gallon in a month and a half. The thing is my friend wants to give me his red that is 3.5", I also want it because the bastard has him in a 10 gallon tank with some other fish. Should I get the red from him and put it in the 40 gallon with the other p's or should I wait to get the other tank and then put him in. But if I get him now and put him in the 40 will my p's kill it? If I wait much longer I think it is going to die in the 10 gallon.