Koi Fish with Recurring Pop Eye

My fish's left eye has been problematic for 1-2 years. But at the very beginning and for most of the time, the eye was just cloudy and nothing else. One day, I used Waterlife Myxazin to treat the fish and his eye healed successfully. It turned clear.

However, since 2 months ago, not just the cloudy eye problem returned, it came with protrusion. On the worst day I could see a very big eye (looked like a button) with not just cloudiness but also some reddish and orange stuff inside--I wonder if that was a cancer developing? I can see an orange lump with some blood veins on it. I wasn't totally sure if that was a lump but anyway, it looked like something was inside the cloudy cornea. Then I used another medicine (since Myxazin was out of stock) called Methylene blue for a few days. Well, it seemed to work again. The eye did really shank. But it did not return to the normal situation like the first time--a clear eye without any cloudiness and reddish stuff.

Well, after a partial recovery of 2 weeks (during which I kept using Methylene blue), the eye turned big again (yes, in spite of Methylene blue). Does that mean the eye disease is now no longer responsive to the medicine? If yes, what is the best way to treat this kind of eye problem?

Hi
Can you provide your pond details please :
Setup :
Pics of the pond
Liters/gallons
Live plants
Nitrogen cycle
Filter capacity
Temp.
Parameters :
pH
GH (hardness)
KH (alkalinity)
Ammonia
Nitrites
Nitrates
Water changes
Tests
Livestock number and species

Is eye "only" swelled up ? Or cloudy ? Or both ?

Quarantine her in hospital tank asap.

Setup :
Pics of the pond: See the picture (fish tank.jpg)
Liters/gallons: 271.32 liters.
Live plants: No.
Nitrogen cycle: Yes, cycled before fishes were added to the tank. The tank also has filter media (those nitrifying stones).
Filter capacity: See the picture. (filter media.jpg)
Temp.: No thermometer. Just use running water, so should be close to the room temperatures? Current room temperature is 29 degrees. So expect a lower temperature in the water.
Parameters :
pH: Less than 6.0.
GH (hardness): close to 0mg/l.
KH (alkalinity): close to 0mg/l.
Ammonia: not included in the test strip.
Nitrites: close to 0mg/l.
Nitrates: close to 0mg/l.
Water changes: roughly 3 days.
Tests: 5 in 1 test strips.
Livestock number and species: 5 koi fishes, raised for 13-4 years.

The left eye is cloudy, swelled-up (not too big today, seems under control? But at least not the normal size), and a bit reddish inside. I can see a lump inside the cornea? Please see the fish's pictures. What are your opinions?

This is posted in the wrong section. Also Koi are really not meant to be kept in tanks. Especially not 5 Koi in roughly a 70 gallon tank. I would remove the sick one to a different tank and just give him salt and clean water. I do not think a medication will help much. The eye may not recover. It looks injured like another one of the Koi is getting at it. The crowding of the tank may cause this. Koi ARE known to be a bit aggressive when kept in tanks. I would definitely work on trying to find the Koi a pond for a permanent home. They can't possibly be happy in that tank.

Hi @kachibi
Excuse me, but do you mean you keep KOI CARPS in a tank ?? Yhis is definitely the wrongest way to maintain Koi.
Not surprising your fish faces problem : fishes are more likely to injure themselves or others in tank that is overstocked.
Do you realise that the minimum volume for 1 Koi is 950 liters ? Koi IS pond fish.
In addition pH should be 7 to 7.5 - GH 8 to 15 - KH 6 to 10
Overcrowding causes injuries and stress that causes diseases.
Find a 5000 liters pond and rehouse your unfortunate Koi asap.
Meanwhile, put the sick fish in hospital tank and try a salt bath.

Thank you for you guys' comments!

By the way, raising the PH, GH and KH levels can alleviate the eye problem?
I think the water condition has been similar since we started raising them. And, other Koi fishes don't have problems. Is it really crucial to raise the levels if I want to cure the eye disease?
And if yes, what should I do to raise those levels?

I told you for trying to cure eye problem : salt bath. Ask for details.
To raise GH KH use dedicated salts you can find in Hong Kong.
Here some good ones I know :
SaltyShrimp© aquarium mineral GH/KH+
JBL© aquadur
Dennerle© shrimp salt GH+/KH+
Sera© GH/KH Plus

I REALLY HOPE YOU UNDERSTANT THAT THE VERY BEST WAY TO CURE YOUR FISH IS TO PUT THEM IN A 5000 LITERS POND.

In Hong Kong, we don't have ponds for normal households. We have been raising the Koi fish from small ones in this tank for many many years.

By the way, the dedicated salts you suggest can both raise the GH and KH and help his eyes (also performs your salt bath function)?

kachibi said:

In Hong Kong, we don't have ponds for normal households. We have been raising the Koi fish from small ones in this tank for many many years.

Click to expand...

Gross mistake !

kachibi said:

By the way, the dedicated salts you suggest can both raise the GH and KH and help his eyes (also performs your salt bath function)?

Click to expand...

I told you "salt bath, ask for details". 2 different things

Again I suspect the eye has been injured by another Koi. This is very common when Koi are kept in tanks like this. You need to remove the injured Koi to a different tank with a .1% salt concentration and see if it helps. Again the eye may never go back to normal... but keeping these Koi in this tank is just not ideal at all.

mjfromga said:

keeping these Koi in this tank is just not ideal at all.

Click to expand...

Actually, none of them !