In generally, the warmer the water, the better the stuff you will find. Summer months under certain bridges offer lots of coral banded shrimp and neon gobies plus a grab bag of angels and blue tang juveniles. Also, it's important to go at slack tides, dead low or dead high. The tides in the keys even vary island to isalnd and so find a dependable chart and get to the site an hour before hand. Most of the bridges have a number of very shallow pilings and it isn't until the middle of the bridge where it gets deep and the current gets rough. You won't really need fins around the slacks. Also, the pilings themselves offer shelter from currents and you can grab them and push off of them to the next piling even if the current begins to rip. Be sure to checkout my transport and handling tips and quarantine sections to do the best for the health of your marine organisms.