This is a discussion on Light and/or Heater for Fighter Fish within the Beginner Freshwater Aquarium forums, part of the Freshwater Fish and Aquariums category; -->
I've got a little siamese fighter in a 15 litre tank (25cm x 25cm x 25cm) that's also got a little filer ...
Are you going for a certain look, or do you basically just want light and heat ? They make very inexpensive heaters for small tanks. I think my Tetra 2-10 gallon heater cost around $7 USD. Chances are the manufacturer of your tank makes a light / hood that fits perfectly. A clamp on type fixture and a clear cover would be another option. In any event, I think a separate heating unit would be best. Hope this helps.