I know a few keepers that have dedicated species tanks for a variety of the hillstream fish and something they have done that I thought was a creative solution to needing biofilm was to buy a kiddy pool from Wal-Mart and leave in the backyard under full sun and just keep swapping large rocks as they cleaned them for a renewable food source. They get covered in biofilm/algae in no time. I'd just suggest putting a few guppies or mosquitofish to eat the mosquito larvae. and maybe a powerhead for water movement.
"In the land of the blind, the one-eyed man is king" Desiderius Erasmus