I started to keep fish in September 2023 and I have 2 dwarf gouramis, 4 mollies, 24 molly fry, 10 corydora catfish and 8 neon tetras. I started with a 40l tank and then upgraded to a 90l tank. So far, 1 dwarf gourami, 4 neon tetras and 2 corydoras have died from swim bladder disease, pop-eye...