Blues are not always easy to keep in captivity. First thing-- they are large for spineys. And skittish as hell. I would suggest as large a tank as possible ( 75 gal min) and provide plenty of rocky crevices as possible to give them shelter. Make sure the rocks are secure to avoid smushed critters. Blues naturally eat flying bugs-- grasshoppers and such. I have seen them knock down bumblebees in flight when the bees were over flowers. The Blues will leap off a rock & snatch em right out of the air! Thats cool to see! I have Blues running around in my rock garden in the yard.