The last time i tried a RTBS with a Firemouth, i nearly lost the RTBS. Both fish were male sub-adult's and the shark tried to dominate the FM, the FM very quickly got fed up with this and attacked the RTBS constantly and i had to split them up.
I'm sure some people have had success with this but there would be a large element of risk.
I'm sure some people have had success with this but there would be a large element of risk.