Dream about having a pet crab is a metaphor for absurdity, light-heartedness and a childish side to your own character. You may need to acknowledge the shadow and negative aspects of your personality. A situation in your life is not what it appears to be. This is an admonition for many major obstacles and challenges that you have to overcome. You need to keep your temper and attitude under control.
Having a pet crab dream unfortunately draws attention to someone in your life who you are not sure if you can trust or rely on. You are not fully recognizing and dealing with some part of your emotions. You are deviating too far from your original plans and goals. It states your fear of losing the friendship and loyalty of an important person. Someone is pretending to be someone you know.
If you dreamt about having a pet crab:
You may be wondering just what your dearest one is up to, as they do not seem able to make up their mind one way or the other. If this annoys you, then going into a sulk won’t really help. What would help is talking this through, if this is possible. This would bring the problem into perspective.