Black Moor W/ Excessively Large Eye

My Black Moor has been sitting in the corner of the tank for the past 5 days. His right eye has swollen quite large, probably about 3x the size it was 7-10 days ago. I noticed today that the outer portion of the eye has completely clouded over.

I've changed the filter media (except for biological filtration) cleaned the tank, checked chemicals, and I have always used salt in the aquarium. Is this a bruise, pop-eye, or something else? Need some help. Thanks.

Hey - looks like it has pop eye. Interpet do an internal bacterial treatment for pop eye. Start medicating as soon as you can.
Hopefully that will do it, although I dont have much faith in it.
Fish can live for years with pop eye.

Can we take a look a your tank size in gallons or litres.
How many fish and which type.
Water stats in ammonia,nitrite,nitrate, and ph.
I agree with spooky if the eye is bulging out its popeye.

Thank you for your replys, I do appreciate it.

I don't own a digital camera (took the pic with my gf's camera on Sunday night) but I can tell you the tank is a 20 Gallon Long, being filtered with an Emperor 280. The heater is set at 70 degrees. There are three live plants in the tank, two ferns and another plant that's name escapes me.

There are two other fish in the tank. A calico telescope and a calico ryukin
Ammonia: Nice bright yellow color, indicating 0 with the test kit
pH: 6.6
Nitrite: somewhere between 0 and 0.5
Nitrate: off the wall at 160

I know water changes have little effect on nitrate. I purchased a chemical this morning to help reduce the level when I discovered it was high, but it hasn't been 24hrs and the levels have not decreased. What else can I do to lower the nitrate level? Is the high nitrate level the cause for the popeye? The other two fish seem perfectly fine, active, and eating well (thankfully). Thanks for your help everyone.

Test your tap water, see if that has Nitrate in it. If it does, I would recommend getting some RO water from your LFS, then adding 50% of your tap water to it and de-chlorinate.

You have a slight Nitrite reading...do you know why ?

Yes - poor water can often lead to pop eye.

With it being internal problems they are hard to treat. But I would TRY to get your nitrate down by 50% and start treating asap.

Maybe Wilder can confirm this...but can you pop the eye from behind it when it gets bad ? Im not 100% on this, but ive heard of it being done....

The tanks overstocked with goldfish.
The first goldfish alone need 20 gallons, then 10 gallons for every other goldfish added.
If your tanks say it 20 gallons you need the at least 40 gallon filter, as they are massive waste producers.
Immeidate water change, might have to think of rehoming two of the them, sorry.

A lot of the swelling has gone down. I believe the eye has ruptured. The Moor is behaving much more normal since this has happened, although it looks pretty bad still. The fish continues to eat and seems much better off than it did even a few days ago. Nitrite is still between 0-0.5 and the Nitrate has dropped to 80ppm.

The fish are just going to keep getting ill due to being overstocked and bad water quality.
You will never get good water quality in that size of tank, as the filter won't cope with all the goldifish in there.