The location variant I had, was from the laguna Chairel, which very close to the caribbean, so at times seasonally brackish.
Species that inhabit the same waters would be Astyanax tetras, Poecilia mollies, and Goby's such as domitor, Awaous, or Eleotris
I would not use other species of cichlids as tank mates when the carpintus are adults, unless in very large tanks, 200 gallons +.

Awaous above, Eleotris below.

Poecilia mollies below, they get bigger than most mollies, so not as easily swallowed. But even they may be in danger of being corned and torn up, unless the tank is over 6 ft.
