I would not leave the light on at night. He look very healthy to me, and so pretty :]
i have the same betta display tank, but my betta died after 3.5 years(he was old) so now there is one lonely snail living in it out in my garage.

. but it seems to me that your betta is fine. just make sure you are cleaning every other day in the small of a tank! at petsmart they have cute little tiny 2.5 and 5 gallon tanks there. they are so cute!! i was thinking about getting one for my baby guppies.
wow i'm a blabber. good luck.