buying livestock

I have a 37 gallon for 3 weeks. Outside of the brown algae (5 snails are having fun) it is totally cycled. I've had 2 clowns in there for one and a half weeks and my readings are all zero and my calcium (I have 3 corals) is approx. 500. Is it safe to add another fish (it will be a peaceful community tank) yet or should I go with a shrimp or two? Thinking of a blackray goby and shrimp.
robin

Sounds like a plan...not an exciting one but one that will keep my impulse in check. Thanks -- I don't want to harm anything I already do have. Particularly since I have only about 32 lbs of LR.
Robin