The Puffer Forum

HELP URGENTLY NEEDED
We have a MBU puffer which we have owned for a year. He is in a 1000Ltr tank with six torpido barbs and six mackerel barbs.

Nitrate and nitrite levels are fine, PH is 7.5, ammonia is low. There is a FX6 on the tank together with other filter systems.
Water changes 10% daily, nothing new in tank.

Peter (the puffer) about two weeks ago developed an S bend in his tail but was still feeding and swimming ok. We tried various people who could not give us much help. Three days ago he stopped eating and yesterday he started to lie on the bottom on the tank on his chin and is keeping the tail end up in the air. Looks really sad and unhappy. PLEASE could someone help me URGENTLY - any sensible suggestions welcome

S-bend is from a tank too small. ANY amount of ammonia is toxic. What's your water change schedule? Plans for upgrade?

library/puffers-in-focus/mbuforyou/
viewtopic.php?f=56&t=150

The tank is not too small, the fish is about 8 inches and the tank is six foot long, 5 foot deep and two foot wide. I did all water tests again last night and everything came back fine, ammonia is 0.01.
He is now just sitting on the bottom of the tank - had a little swim around last night where he looked normal again then straight back to the bottom where he still is this morning.
Really need some sensible help please

Please provide answers to all of the questions above in red.

450g for an 8' fish may be fine but what about tank mates? Something is causing ammonia not to be broken down in there.
How long has he been in that tank & what-sized tank did he come from, how long ago?