I am confused with your measurements. there are 3 measurements. Length that is like left to right when looking at it. Then Depth which is like front to back then height which is bottom to top.
The most important to find out if it is big enough is length then height of the tank equats to how bright the light will be at the substrate level.
The tank is 10" from the substrate to the surface. The tank from left to right is 12" so I need a fixture that is approximately 12" long.