I have a 55 gallon tank with 6 long finned zebra danio, 6 long finned serpae tetra, 4 panda cories, one SAE and 2 nerite snails. I’ve had this tank for over two years and it’s stable. I would love to add the super blue royal tetras (6) to the mix. Is there an issue with the danios? I’m also planning to up the amounts of the schools as well one the new tetra settle in - danio, serpae and cories all up to 8. Thanks!