The texas are going to get big, if you have 2 males dominant will probably kill subdom, if 1 male and 1 female, they will probably breed and kill convict. Good chance the male could kill female as well since there's not much room to run for large fish in a 55. Would be better to do a small group of convicts or Honduran Red Point's, or similar amatiltlania species, and some non-cichlid tankmates. Ameca splendens would be great, because they are quick and tough, but most larger livebearers or tetra should work