and
Both hardy, cheap, interesting, aggressive.
Not sure how happy I am with that last one, but they fill all the other requirements.
Also, about 6 of the littlest hermit crabs I've ever seen, 2 snails about the size of quarters, and a hermit I got about 2 weeks ago, who's shell is about 1.5 inches across.
So far salt water is proving to be really interesting. The fish are definitely cool, but they're just part of a big creature filled machine.:spam: