My younger sister has FINALLY decided to get rid of the 6 goldfish in her 10g. This will be non-planted, but will have some driftwood. the filter is an Aqua-Tech 10-20, I hope to convince her to get a aquaclear filter. What are some good fish to keep? I have looked into pygmy cories and sparkling gourami, she doesnt want a betta because she would prefer a school of smaller fish.