I use Zebra snails and they don't eat my java fern, Bolbitis, or Anubias.
Also, depending on the pH of your tank, you could try a clown pleco. They
grow to 4" and don't mind harder water and a pH of 7.5 (water conditions
similar to rainbows).I have not kept clowns with my Tanganikyans but as long
as your tank has lots of hiding places they might do ok .