MUCH-loved POND FISH appears to be dying… HELP!!?

Question

I have a huge, beautiful, white female pond fish (not koi) in a large 90 gallon aquarium with a fantastic top-of-tank 600-gal.-per-hour filtering system with a few other pond fish. The rest are all AT LEAST 5 years old (some pushing 10). I’ve had them their whole lives …all very healthy until recently.

June 13th (last month), she developed a case of pop-eye in her right eye. I immediately did a partial water change and treated with Melafix. The swelling in her eye went right down - she seemed normal for past month.

This morning, she was sitting on the bottom (unusual), but as soon as she saw me, she began swimming around as normal. Later, she spent less time swimming, and more time “resting” on the bottom.

I tested water with a color-coded test kit (nitrate, nitrite, hardness, alkalinity, pH). All came up “acceptable” except for the nitrite level. That turned up an odd color, so I did about a 30%-40% water change at around noon. I treated with Melafix. She perked up, but...

Answer 1

I know you don't want to hear this, but your problem is probably coming from an overstocked tank. Your other fish may be affected but just arn't showing it yet. What I would do get a bigger tank or the condtion is just goin to get worse. I'm sorry. I mean you said it yourself these fish are "POND FISH" and love lots of space which I'm sure they have in your 90 gal but it's not enugh for them.

Good Luck!