Wikipedia
There are around 1,300 species of freshwater crabs, distributed throughout the tropics and subtropics, divided among eight families. They show direct development and maternal care of a small number of offspring, in contrast to marine crabs which release thousands of planktonic larvae. This limits the dispersal abilities of freshwater crabs, so they tend to be endemic to small areas. As a result, a large proportion are threatened with extinction.
Usage examples of "freshwater crab".
Still we got on pretty well, till I happened to look behind me -- my attention being attracted by a noise of something crawling over the stones, and perceived sitting upon a rock in my immediate rear a huge species of black freshwater crab, only it was five times the size of any crab I ever saw.
Squill evicted a small freshwater crab with a toe, watched it scurry for the water.