I've been considering downsizing my tank to a 40 from a 55, and was wondering if what I already have would do fine in that size or if I'd need to give up some fish. Current stock is 6 swordtails, 6 neon tetras, 4-7 guppies, 8 zebra danios, 9 khulis, a bn pleco, and various types of shrimp. Also...