Minnow attacking goldfish

[Bollyeyes]

Hi all. I have a 9 year old goldfish who’s health has declined in the last year. It started when I put a Plec in the tank the plec developed a taste for the goldfish tail. I separated them as advised on here. Since then he has lost all his colour and has gone pure white. I also believe he has now gone blind or is very partially sighted.

His tail has grown back but I keep noticing red streaks in his tail. I’ve noticed that a white cloud minnow is nibbling at his tail. This minnow seems to hang around the goldfish and nip over for a nibble quite often. None of the other minnows or tetras are doing this.

I’ve tried googling help but all it returns is goldfish attacking minnows. Not the other way around…

What can I do and any ideas why he has gone white? Tia x

 

[Aiken Drum]

Please take a read through the "unhealthy fish" sticky and give as much detail as you are able.

https://www.aquariumadvice.com/forums/f17/before-posting-about-unhealthy-fish-read-this-32451.html

It doesnt ask for water temperature in the sticky, but can you give that also.

 

[Autumnsky]

Having a stress can effect some animals. Please add what kind of goldfish.

A low pH can affect a Goldfish. It seems odd to just change color at 9 years old. I can also check with some long time pond fish keeping friends if they had noticed that. But knowing more about the pond would help.

Any additions of chemicals like algae treatment, or ???