Our online calculator will help you calculate the required wattage for lighting of aquarium of any size.
If your aquarium only fish and no living plants, in this case you the minimum be sufficient lighting for your convenience only.
Usually the fish is too bright lighting is not necessary - in fact it will only cause stress to them and as a consequence, disease and other problems.
At the aquarium you can install a lamp with any spectrum of luminescence, because it all depends on your tastes.