Fish don't care what kind of light it is... though too much would certainly cause them some stress. They'll be just as happy under T5's, T8's, T12's, LED
's, CFL's, PC
's, Halogens, natural sunlight, etc as they are with no light. You don't *need* lights on a fish tank, as long as there is some ambient light in the room. Since this is going in a business, I would assume it's there for enjoyment, making a light more of a mandatory piece of equipment. LED
's and MH
's do have a way of making the water 'glisten'. They won't make the fish look any different. I would choose something that isn't very intense, as to help keep algae at bay. 14,000k-18,000k would definitely show off their colors well.