Hi everyone! I’ve had one of my guppies in my 10g guppy tank for a few months now. I’ve noticed he’s always had a small bump on his tail, but as everything else was normal I thought nothing of it. Last week it at least tripled in size, now round and bubbly looking. As he was also missing a huge chunk out of his tail (my guess was the yellow guppy) I moved him to my 5G quarantine after giving it a quick water change. Both the quarantine and main tank were tested and have normal parameters. My guess is lymphocystis, which fits the situation and doesn’t have a cure but supposedly goes away after a few weeks. I can’t tell if the mass is getting bigger. I’ve been trying to treat with seachem paraguard in case it helps, which hasn’t so far. Is there any other disease it could be? He’s still eating and acting normal but seems slightly weighed down by the mass.