RTC & TSN both get pretty big... what size tank are you thinking of putting this mix in? To answer your question more direct... yes, they can mix. Just keep in mind that if the catfish are too big they will eat the cichlids. RTC are always hungry and will eat most anything!!! RTC also grow very quick... mine grew from 3" to about 7" in around two months. It also would attack my other two catfish all the time. These two fish grow very big and they grow fast too... you need to keep this in mind. I got rid of my RTC as I knew I could not house that fish much more than the two months I had it. My RTC was in with a 10" Silver Arrow, 12" Jaguar, 8" JD, 10" RD and a 9" Buttikoferi, which were all bigger than the RTC, along with the other two catfish about the same size as the RTC. They were in a 265g. IMO, RTC should not be housed in a tank, but rather a pond. I currently have a Perruna catfish and a Granulosus catfish, which grow a lot slower in with my cichlids and they are fine, however I will not be able to keep either long term.