I have a 10 gallon tank with cory fry. The corydoras are about 2 months old. There is a sponge filter in the tank. The cories eat Fluval bug bites, hikari first bites, and tetra shrimp wafers. I have Java moss, duckweed, Hornwort, and Marimo moss balls in the tank. Yesterday, I noticed 1 cory fry struggling to swim and he kept floating to the top. I do daily 60-75% water changes. I'm not sure how to help him. He seems to be really struggling not to float.