Regarding stocking, I started with 15 tetras and the pleco. A week later I added a gold severum, 5 geos and the EBA. Almost 5 months in, I lost the severum to a bad prolapse. A few days later I added my current two severum. I lost my smallest tetra to a predatory attempt by the green severum the first night. A month or later, I lost a big tetra to dropsy. Another month later, I lost my second smallest tetra to a swim bladder issue. Ive had no other health or aggression problems. To be safe, you could add the severum last.