1.5 feet aquarium, is quite an small tank. The most you can have is about 40L of water / 10 gallon of water

It is possible to get off the shelf Aquarium lamp for such aquarium size, try Pet family at Taman megah but the amount of w/gallon will be very limited.

I have seen once a 36W PL light Fitting case for 1.5 - 2 feet tanks. But can't remember where I seen it.

Alternative will DIY lighting.

BTW how much lighting u intended to have for your riccia tank ?