Do you mean SA lampeye tetras (moenkhausia) or african arnoldicthys red eyes?
If lampeyes, you should consider growing them out to max size before mixing with mid sized cichlids. They do get to a healthy size but it takes a while, I think a big GT would still dine on them full grown though. The lampeyes I've had seem to join in with other schooling fish when the opportunity presents itself.
I have no experience keeping arnoldichthys but I've always suspected they would be a poor choice for a dither due to their more slender build, seem like an obvious target for predation. They get about the same size and build as giant danio but are much more expensive ime.
