Weird Situation-fish at top

[sweetness8t5]

So, I did a water change yesterday, normal procedure. Nothing unsual about it. Maybe took out a little more than normal, but I do that at other times and this never happened before.

So I put the new water in (treated), and turned the light on. Since it's an incandescent light and their known to heat up the water... I decided to leave it on to make sure the water warmed up some. This is how I ALWAYS do this.. for about a year now.

Well, I'm not sure how long after that... I noticed all of my fish at the surface. I didn't know what to do.
I contemplated changing the water again, but I did everything I normally do.
I turned off the light thinking maybe the water got too hot or something maybe creating less oxygen in the water(idk).

Nothing, still at top. So I decided to make and put an aerator in there, and watched what happened.

In about 5 minutes my fish were back to acting normal. Today I woke up, no dead fishes and everything is normal.

I really don't know how to explain this or anything.
Like I said.. I did everything how I normally do and such. And they were fed before I did the water change, so that couldn't be an explanation.

IDK.. anybody else have seen this before?

I decided to post this because maybe I'm overlooking a potential serious issues... I really doubt it, but who knows.

 

[lyquidphyre]

See my answer over at LJ =oP

Actually.. I'll copy and paste:
How how was your water? Usually when they are on the top they are suffocating/gasping for air. This can be, like the previous poster said, because of surface agitation or if the water is too hot, the heat sucks out all the oxygen.

Adding the aerator is EXACTLY the right thing to do when that happens.

This has happened to me a few times in the past (because of a screwy heater) and in severe cases I dumped tons of ice and changed out the water with cold, cold water.

 

[Lonewolfblue]

Do you have a thermometer in the tank? How warm was the water? Another thing that can cause them to surface is if there's a major change in the water chemistry, such as the hardness (kh) from the city water, etc. And until the fish acclimate to a change in water chemistry, they can act differently, or even die. But it sounds like it was warmer water and the surface aggitation is the first thing you do when the fish are surfacing. Either that or another PWC with a little cooler water, say 3-5 degrees cooler. And then add the surface aggitation.

 

[BillD]

It would be odd to be short of oxygen after a water change, as normally, the water coming from the mains is supersaturated with oxygen, and when it warms, releases it in the form of visible bubbles.