You should really return the gold gourami. They get way too big for that size tank; a six inch fish won't be happy in a 29 gal tank. They can also turn nasty as they age.
But kuhli loaches are great! I have about 9 in my 29 gal and love them to bits. :3 When you return the gourami, you should get more kuhli loaches. They are highly social fish and do best in groups of six or more kuhli loaches. They can also be reclusive in small groups.