Upside-down catfish water change death

[Chikadee]

Hi everyone! I just returned to the aquarium hobby after a few years hiatus. We set up a peaceful 10gal community tank. It's been cycled and the water parameters are all normal. We recently got an upside down catfish that was happy and healthy except after water changes. The first time, he seized up and started floating around the tank. None of my other fish were affected at all. He looked like a goner for sure, but somehow managed to pull through. He seemed completely back to his normal bashful self after half an hour. Then I changed the water again last night, and he had another seizure-like fit and didn't make it this time. It was a 20% water change, temperature matched with dechlor mixed before i put the water in. All the other fish seemed completely unaffected. I checked parameters again, and everything seems fine. What happened?

 

[AndrewH]

Seems pretty strange should be fine if the temperatures are the same. What about the pH? Does the pH from the tap match the pH in the tank?

 

[AndrewH]

"Changes in the pH, especially sudden changes, can prove harmful or even fatal to fish . As the pH rises it increases the toxicity of chemicals such as ammonia. It is an important factor to monitor during the break-in of a new tank. pH changes are particularly hard on young and sick fish."

Taken directly from http://freshaquarium.about.com/cs/waterchemsitry/a/waterph.htm

 

[Alaris]

I was also going to suggest that it could be your pH.

 

[happygirl65]

Ditto. Check the pH. I have to do relatively small changes on smaller tanks because the pH is much lower coming out of the tap than it is after it sits for a while.

Also your catfish could have just been a weak specimin that could have gone through some major stress at somepoint even before you got him that left him permanently damaged or in a weakened condition. Some fish are more sensitive than others.

If you want to try again with the upside down cat I would say go for it, but you might want to take a sample of tap water and test the pH right out of the tap and then let it sit out overnight and test it again. If you are seeing a difference then you may want to age your tap water to prevent further problems with sensitive species.

(Aging water is pretty common practice for discus keepers for example as they are sensitive to eradic changes in pH)