I used to have a fishroom,heavily insulated with no windows, 12ft x 8ft and and a light over every tank (about 50), heated by a one kw element and a fan going all the time and heat was never a problem. Unless you have massive lights in which case I would confer with the previous advice about diverting the heat away. Don't forget you are paying for heat even if it comes from lights, so if you can use it to preheat water you may save a bit.