Your only option really is more Fancy Goldfish. I'd suggest 6 max, less if you don't have excellent filtration rated for above 180-gallons, and I'd trade the Bristle Nose in for a Common Pleco if you must have a Pleco, as they are more able to tolerate lower temperatures and the high amounts of ammonia produced by the Goldfish. Really though, Goldfish should only be kept with Goldfish.