the jewels shouldn't care much about the substrate, they're too busy looking sideways and upwards for other animals. they may verywell dig a pit though if you get a pair that breed (which is really the only option besides a single). I have an overturned strawberry pot and they use that to spawn inside. they will then remove the larvae from the eggs and place them on the substrate inside the strawberry pot. I keep the pot dug into the gravel so the larvae/fry stay inside the pot until I notice them and can shut the power filter off. this keeps the struggling young fry from getting sucked up by the filter for sure. I would imagine the parents would dig the sand out inside a cave or whatever you have to nest the fry. As for plants in the sand, I don't know what would happen there. I have fake plants in their 29 and havn't seen them even try to move the gravel around but you never know. KYle
