You should never put two regular crayfish in a 20g. When you have small fish with them you are going to have no fish in that tank soon. You are also going to only have one crayfish soon because they need more space. If you have shelters for them then they will be fine.Pontiff said:I've got a blue and a vanilla crayfish in a 20 gallon long tank, along with a few other small fish. Should I put them in a breeder container with some gravel when they molt, so that the other crayfish can't get to it while it's vulnerable?