I have a 3" Golden Dojo Loach in a 39 Gallon Tall Community Tank, and I recently got a 40 Gallon Breeder Tank, with sand substrate and am thinking of moving my Dojo into the 40 Gallon. He is very happy in his current tank, swims around crazily, and loves chasing his reflection. But do you think he would be happier with a sand substrate vs. being in a tall tank?