@Krishnaa_Murari@narayananh@swethasridhar95 They aren’t fiddler crabs. They are brown land crabs (Cardisoma), much bigger.
However you’re correct that they normally drink brackishwater, but can take both fresh and salt water too if necessary.
@mtanichthys Growing up in my town we had a wet market where fisherman brought fresh (often live) catches for sale right from the river.
I’ve seen this species there a couple times. It was wonderful