You can feed a tank by feeding imaganary fish (sprinkle fish food in there to just rot by itself) or put in a raw peeled shrimp and let it rot. Traditionally people have seeded tanks with damsels, but it is very hard on them, especially their gills, so it should not be done.
Not that it is too far off, but your specific gravity is a little low, 1.025 is the "normal" reading. Some people (and most LFS) keep it low in fish only systems to help control parasites.