Don't mix the colours. One nice thing about tropheus is that if you can get a colony in good shape, they'll normally breed. If you can sort out a decent rockwork organisation you can just pull out the young every 3 months or whatever, and they are easy to sell for good money! However, mix colours and you will end up with fry that are worth approximately zero instead of 5+ dollars apiece for good colours as they will hybridise very willingly, and the colours do not improve.