Backing up to the initial several posts in this thread...you have soft to very soft water, and a small tank (10g). Your best options are "nano" size fish. The pygmy cories, and dwarf rasboras (Boraras species), Ember Tetra, and similar. Sparkling gourami (the pygmy gourami) in a trio. These fish will provide more interest as there will be more of them in what is a small tank, but one suited to these fish. Assuming floating plants, and a sand substrate.