One of ours constantly is burrowed in the sand. There is nothing threateneing in the tank that they are living in (African Cichlid Fry) so I don't know why he/she constantly burrows. But they have taken a liking to the taste of the fry. The other comes out every night and hangs out in the greenery. Make sure you have a hood on the tank that they can't get out of. They really aren't that fun to watch since they are burrowed when the lights are on. But at night they are pretty cool to watch swimming out and about in the tank. Maybe mine are just scardy cats and that's why they never come out.