...just a comment on the fiddler crab part of your message. Fiddlers need a specific gravity of 1.008 - 1.014, coral substrate, a few mangrove plants, a beach of sand, and most of all, crabs of the other sex

, with that you get pregnant females, who develop a beard of eggs, but those need to be released into high salinity conditions (reef), and then they crawl their way back to the brackish water. I'm hoping to attempt this with my new reef set up by using the refugium, we'll see!