.If your tap water parameters are in the neutral range (pH 7 ish, or lower, with low to moderate hardness) aquarium strain angels will work for a while.
If your water has a high pH,(7.5 and above) with moderate to high hardness, either a pair of smaller Amatitilantia (Cons, nanolutrus ) of small rift lake African cichlids.
Or better yet, no cichlids at all but instead ...... stocked either smallish tetras or live bearers, that are geographically appropriate to your water parameters that don't grow over 3.5 " (6 cms).