Thanks so much for your kind reply! I also think my poor green glofish has tumor. This bump started since late Dec 2020. He is doing well and eating well. At this point, i haven’t noticed anything on other fish in the same tank. I just moved all my fish to a bigger tank. I was thinking this might be related to stress or poor water quality. But my tank is tested within the normal readings. I sure hope my green fish is happier in the bigger tank. Thanks!