Hi David,
A crab in dreams and visions usually indicates that you are dealing with a person with the attitude of a crab. Such a person is usually secretly attracted to people that they can score from, financially (like a natural crab being attracted to fresh-water which symbolizes financial provisions) or a crab being drawn to the sea, on beaches, indicating that such people maneuver themselves in such ways that they are ready to grab all the provisions (food) that is “washed out by the sea”. Such people try to hide their motives and plans just like crabs which are always hiding and running away for shelter. Everything they usually do is to score or to receive financial blessings or provisions. They grab and go, ready to flee or to run for shelter.
Blessings
Mandy