No, I do not have them in the same tank...I was afraid of Arnold thinking he was a snack. Although I haven't feed him live food, I just didn't want to take the chance. When Deebo gets bigger I may put them together...but for now they are in separate tanks.
The substrate in Arnolds tank is a mix of playsand and eco-complete...it use to be a well planted tank, then it was home for my Africans...they took care of the plants, I moved the Africans and just never changed the substrate. In Deebos tank it is just playsand.