nope they are not ok. i had them together for not even a week and the ck started nipping the bgk. i had to put a divider but with the top still open for my other fish. that didnt help either. i had to put the ck in a 20 gallon tank for a week before he went into my main tank. i also has that tank full of plants and hiding spots. also the ck outgrew my bgl 2 to 1. thats just my experience, maybe others have had better.