my goldfish are sucking air

Question
I just bought a new filter for my fish tank and now my gold fish are up at the top of the water most of the time "sucking air".  Do I need an aerator? The new filter is a Tetra Whisper power filter, nothing really different than the last one, just alot quieter.

Answer
Hi Jackie;

Having a new filter is similar to having a new tank. It has to "Break In". The beneficial bacteria that lives in the filter and usually consumes ammonia and nitrites hasn't developed yet. The fish are experiencing burned gills from the toxins. Make a 25% water change and do one again in another day or so. This will help the fish feel better. Test the water for the levels of ammonia and nitrites. Do the partial changes until they go down and stay down. Even a daily change isn't too much as long as the temperature of the water is the same as the old, and use a good water conditioner. It could take several days or a couple of weeks for this to get back to normal. Testing will help you know when it happens.

At Your Service;
Chris Robbins