I realise that swim bladder disorder comes from overfeeding, but this came out of nowhere! I feed my male veiltail betta 3 hikari biogold pellets each day, with one day of the week fasting. Today, I saw his tummy was a little rounder than usual so I only fed him two pellets. Immediately, he floated onto his side!

Oh no! He only floats at the top and tries to lean agaisnt the tank wall to keep upright. Last month, he had swim bladder disorder, but after two days of fasting an eating a cooked, shelless pea, he went back to normal. What was the cause of his sideways swimming, and what can I do to help? Thanks.