Im not sure about the musk, you can do a mud turtle though. they only max out at 5 inches. hairy puffers get very big so thats a no, you can do avocado puffer, pea puffer. Right now in my 29 I have 2 angels, 1 rainbow fish, ! paradise gourami, 1 smaller rainbow shark they all do well although a bit of chasing and nipping now and then, but other than that there ok. If you want a predator your best bet is a small puffer or a smaller cichlid like an electric blue acara, ram cichlids are cool not really predatory though.