My goldfish is dying.

Question
My goldfish appears to be sick, with black spreading all along his fins to his mouth and eyes. He stopped eating today, and I fear he's worsening.

 My tank has been set up for about a month and a half now, holding only one goldfish. I am using a carbon and cotton filter and a biological filter in a 3 gallon tank. The pH is 7.2, and the ammonia is 4.6. Is it Black Smudge Disease or is it ammonia burns? How do I treat him? I tried changing the water but the ammonia level shoots up again. What can I do?

Answer
Hi Delilah;

It is ammonia and nitrite burns. The tank is too small for goldfish, as they are messy fish. They can't help it they are just major ammonia producers. A ten gallon is the minimum a goldfish should be in. Many people keep them in small tanks and bowls, but they usually don't survive for very long. Their life span is 10 or more years and they get 6 to 8 inches long.

Make daily water changes of 50% until you can get him a larger tank. Don't change the filter or clean it until the ammonia stays down. It is still trying to cycle and if the beneficial bacteria growing in the filter is removed with the media, the tank will never cycle. This beneficial bacteria eats ammonia. Without it, the ammonia will always be high.

Feed the fish every other day (if he is eating at all). Feed very little food. The more food he gets, the more ammonia he will make.

Followups welcome

At Your Service;
Chris Robbins