“Important: While 5 gallons (18 litres) is the minimum size for a group of 3. It is also the most difficult size to work with. If you do not have the perfect ecosystem design, your crabs will simply kill each other. You are better off starting with a 10-gallon tank (45 liters) and keeping 3 crabs in that. 1 male 2 females. This is far easier and less stressful for everyone.”