There is a Dwarf Loach, Botia sidthimunki that generally stays at about 2 1/2 inches in the aquarium (though they can get over 4 inches). There are other loaches that could be considered, though they're not dwarf. The Yo-Yo Loach, Botia almorhae, the Stiped Loach, Botia striata, and the Skunk Loach, Botia morleti all stay considerably smaller than the Clown Loach.