The Puffer Forum

Hey everyone, one of my dwarf puffers hasn't been himself these past two days. He has been hanging out in the back of the tank behind some decor, and very, very slowly swimming around. He is still interested in watching me and the tankmates, but no longer follows us around the tank. I tried feeding last night and again this afternoon and he has not been interested in the food. Last night I noticed a small, white bump just behind and to the right of his anal fin. Additionally, some of his posterior spots appear lighter.

Answers to the above questions:
1. Ammonia= 0, nitrites= 0, nitrates= 5, pH= 7.6
2. Tank size 20 gallons, containing 2 dwarf puffers and 3 zebra danios
3. Feeding frozen bloodworms every other day. Water changes 20% twice a week, tap water is slightly basic (typically around pH 8.6), so API Proper pH 7.0 added to lower pH
4. No changes in the last week or so
5. Tank has been set up for 8 months, cycled with zebra danios. DPs introduced 6 months ago

Sorry these pictures aren't the best (he's a little camera shy!), but you can see the size and location of the bump. Any guesses as to what it is/what I can do for the little guy?

Is something sticking out of his anus?

+1 is the anus clear? The bump itself looks to be a mm behind the anus. Are there any other bumps? Not sure why it originated but the placement would make the fish feel awkward moving is caudul fin probably why its acting off. It appears to be healthy otherwise, not emaciated in the least. I would monitor and verify the bumps do not spread either on itself or to other tank mates. If its possible move it to a quarantine tank for observation.

The anus appears to be clear, this bump is too far to the right of the midline to have originated there. I will continue observing him and his tankmates