motoro ray

I have a 6.5x2.5×2.5 tank that is stocked with 5 red hooks 2 lapradei 1 endlicheri 2 tarpon 1 african pike 1 african arowana 1 lima shovel And now a newly added 10" disc male marbled ray. Question the tank has 1.5 deep black petco sand on the bottom, bout 6 months old. No issues on the...