When bringing home self caught inverts, you need to be aware that some will carry parasites and diseases with them that won't harm the animals at sea but can overrun a closed system tank. Any invert that holds water (i.e. anemones, cucumbers, corals, etc) should be quarantined for at least 3-4 weeks before adding to a main display tank. This will give any disease or parasite a chance to become apparent or die off from lack of host.
Items like crabs and shrimps should be safe but snails are known disease carriers. I would suggest you always quarantine any new item before exposing your tank.
Hope this helps