How can we help our black moors??

[BittyBlue]

The scales surrounding the eyes of our 2 black moor fish have started to peel. It's affecting one eye of each of the 2 fish. We have a 180 gallon tank and none of the other fish are affected. We did a water change and tank clean 2 weeks ago. We did have a moor (named Ty) pass just prior to the water change but he was almost 3 years old and his scales started as black and slowly transitioned to look like a gold fish after his first year in the tank. Ty's coloration change started with scales around his body, not eyes. Could this be the same thing or something different? These 2 moors don't seem to be in any distress. We have 2 bubblers in the tank, some sand and small round glow stones. There is no other decor items in there currently. We do have several other fish: oranda, ryukin, regular gold fish, a comet and 2 dinosaur eel type. This tank is far from overwhelmed in reference to how many fish we have.
After the water change, we did try to introduce 2 store bought gold fish from a trusted local store, and the dinosaur eels did target the new fish. The new fish have since been removed and placed in a secondary tank. We did this in assumption that they were targeted to due to being much smaller than the rest of the population.
How can we help these moors??
Thank you in advance!

 

[Colin_T]

Pictures of the fish and one showing the entire aquarium?

What's a dinosaur eel? Post a picture if you don't know the scientific name.

When you did a water change and tank clean two weeks ago, what did that entail (the tank cleaning part)?

How long have you had the black moors for?

What are the tank dimensions (length x width x height)?

What is the ammonia, nitrite, nitrate and pH of the water (in numbers)?
What sort of filter is on the aquarium?
How often and how do you clean the filter?

How often do you do water changes and how much do you change?
Do you gravel clean the substrate when you do a water change?
Do you dechlorinate the new water before adding it to the aquarium?

What do you feed the fish?
How often do you feed them?

 

[MaloK]

Excluding illness and water parameters.

I can tell from experience that the fast swimming and more ravenous feeding habits of comets compared other goldfish. Will lead fancy goldfish to get hurt. Their basic physical traits are a lot more resilient and aggressive.

Poke in the eyes and cut from fins.

Remove the comets.