Please help sick Blood Parrot

[SciFyDi]

Hi,
My blood parrot started to look a little weird a few days ago. He started turning white and looked lethargic and is breathing heavily. Yesterday I thought he looked really bad so I dumped 80% of the tank and started Kanaplex. I don’t know if the water chemistry will be accurate. Today I noticed his bottom is swollen and he has developed black patches on his underside. Sorry it’s hard to get clear pictures. He isn’t eating and swimming lopsided. None of my other fish are sick. He lives with two Blue Botia’s, another blood parrot and a upside down catfish in a 55 gallon. He is about five years old and has always been perfectly healthy. I change out 70% of the water once a week. Thank you!

[Colin_T]

It has an internal problem and it could be something like Fish TB or internal organ failure. There's no cure for either.

Check the water quality for ammonia, nitrite, nitrate and pH. It will probably be fine but check it anyway.

Do a huge water change and gravel clean the substrate.

Clean the filter if it hasn't been done in the last 2 weeks.

Increase aeration/ surface turbulence to maximise oxygen levels in the water.

If there's no improvement in 24 hours I would euthanise it.

[SciFyDi]

Thank you for the reply.

I found him floating at the bottom of the tank. At least he didn’t suffer much and it was quick. I think I knew it was bad because no one else is sick. I’m worried about the other tank mate he has been with since a fry and will eventually have to get another one. I’m going to do a huge water change and continue with the Kanaplex just in case.