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I would be careful adding crayfish to a tank because many times they carry deceases that if pasted onto a fish can kill. So qt time would be required in my opinion. But they aren't my fish either. And I would check on the species because, if I'm right, other species can have blue morphs too. The one your looking for is the alleni. Their is also a white form too, if it is an alleni.
55 Gallon Community
40 Breeder Peacock cichlid Grow Out
10 gallon empty
5 gallon Guppy Tank
2.5 gallon cylinder Crayfish tank
1 gallon empty