Hi dter! Sorry it took me so long to respond, I've been up to my eyeballs in lab work! Some great loach options for a 29 gallon are kuhli loaches (pangio sp.), sidthimunki/ dwarf loaches(ambastaia sidthimunki), and zebra loaches (botia striata). They all stay fairly small and are quite peaceful. I would recommend a group of 6! With your stocking plan, 6 of any of the species I mentioned would work quite nicely, and appreciate very similar water to you tetras and dwarf cichlids!