Hi,
I have a 5 gallon Eclipse Biofilter aquarium with two mini Puffers (Tetraoadon Travancorius)in it. I bought the fish three weeks ago. Two weeks ago I did my first 10% water change and the larger fish immediately started having trouble swimming and spent a great deal of time floating upside down, but seemed other wise alert and OK. I assumed the new water was too cold since I had done all the other tests. By the next morning the fish was back to normal. No other unusual behavior until the day before yesterday when just after I fed them thir afternoon meal the same fish went belly up again. After a few hours it was fine and swimming normally again. I have been feeding dried blood worms. I tried switching to pellets that sink thinking the fish could be gulping air, but they won't eat them. My fish is currently upside down, went belly up just after morning feeding, and I would welcome any advice. I live in the country and our pet store people seem to know NOTHING about the fish they sold me.

Thanks and good luck with your problems,

Hello Aworthington,

Your little puffer is "puffing" himself up.
This isn't a good habit for the little guy to start practicing.
Sometimes they can puff themselves up and deflate with no problem, but sometimes problems do accrue where the water pressure causes their inflation valves to press shut making it to difficult for them to deflate... If they are unable to deflate, it will unfortunately cause death.

Stress is the #1 reason for puffers to puff themselves up.
Some possible causes could be:
-more then 1 male in the tank
-being hungry
-dislike of food (they are very picky eaters)
-any level of ammonia or nitrite
-high level of nitrate (over 20 ppm)
-water changes (very small water changes must be done more often so that water chemistry (Ph,Gh, Kh, and temperature) are not disturbed and to ensure nitrate levels do not go higher than 20ppm)
-not enough room (dwarf puffers need at least 5 gallons of water per puffer - They are very territorial and need the space)

Water Chemistry should be constant:
Ammonia 0ppm
Nitrite 0ppm
Nitrate 1 - 20ppm
Total Hardness (GH) and Alkalinity (Kh) soft/moderate
Ph 7.0
Temperature 78 degree F

Is the fish thats puffing eating? getting picked on? or anything else that you may notice?

They should be OK as juveniles in a 5 gallon, as they reach maturity, you'll want to move them to a 10 gallon.

Puffers express their dislikes by puffing... unfortunatly it can cause death if too much pressure prevents them from being able to deflate.
You'll want to watch closely as to what's different when he puffs... This way you can try to prevent the puffing.
It will become habit for the little guy to puff every time he dislikes something - this increases his chances of death.

You can say they are very demanding;)

The little guy probably discovered that he could puff when you made a water change that was slightly a different tempature... and perhaps he didn't like the food you fed him the 2nd time he puffed.

If you have anymore questions, concerns or anything, I'm here to help:D

Kae