I have a 55 planted tank with Denison Barbs, Rosy Barbs and Hillstream loaches and a few Amano shrimp that I hardly ever see. I realized that my driftwood has a branch that is just above the surface of the water but is still under my tank hood. The thought occurred to me that a Fiddler crab might work in the tank if the Rosy Barbs won’t pick on them. The barbs have not killed the shrimp but they are good at hiding. Anyone have experience with fiddler crabs and similar type fish?