I have 2x 4" P.ultramarinus housed individually in 5 gallon aquariums.I house them as terrestrials with the opportunity to burrow.They've shown no interest in burrowing but rather stay out in plain view the majority of the time or when disturbed head for their corkbark retreats.Staying out in the open in a bonus as they are a very striking spider to look at.They are doing well in temps in the range of high 70's-low 80's with and RH value around 75%.They also have huge appetites and will take pinkies(prekilled)....peace...