HELP! Red spots, swimming upside down, white patches

My black line rasbora has gotten very sick seemingly overnight.
Had a new fish I introduced die, so I think it might be parasites? Tony, the rasbora has been slowly developing some red gills and spots, but it got tremendously worse today, he’s now swimming upside down and looks very pale.

PH- 8.2
Nitrates -40
Nitrite- 0
Ammonia - .25

20 gal
25% water changes weekly
my tank is not doing good right now and I don’t know why, I think it’s overstocked and I want to move fish into my 35 gallon. I’m afraid of potential disease transfer though. I really don’t want to loose anymore fish and would like help saving this fish.

My black line rasbora has gotten very sick seemingly overnight.
Had a new fish I introduced die, so I think it might be parasites? Tony, the rasbora has been slowly developing some red gills and spots, but it got tremendously worse today, he’s now swimming upside down and looks very pale.

PH- 8.2
Nitrates -40
Nitrite- 0
Ammonia - .25

20 gal
25% water changes weekly
my tank is not doing good right now and I don’t know why, I think it’s overstocked and I want to move fish into my 35 gallon. I’m afraid of potential disease transfer though. I really don’t want to loose anymore fish and would like help saving this fish.

Update- scales falling off!? Do you think I should just euthanize him at this point? If there’s any chance of saving him I want to try. This fish has been healthy for two years with me, I don’t know what happened

 

Goodness gracious friend, I'm so sorry. Although I research a lot, I'm not experienced with disease (I just don't get diseases where I'm at - luck?) I guess ulcers by introduction of sick fish, new chemicals, old age maybe, low pH or ammonia. Since they live awhile I don't think old age is the cause but I had a 2yo yellow moscow guppy named Lolli pass due to ulcers which looked eerily similar to you. He had a ragged tail, lost scales/color and had red, inflamed skin. He appeared to get better for a few days but it didn't last. I didn't have a chance to euthanize...The only difference I made was Prime for the first time in 6 yrs. I had a previous issue with Prime - it killed dozens of minnows and goldfish. I thought it was expired or a mistake. Apparently you can dose up to 5× the amount without issue but I don't know, as soon as I dosed the correct amount without using it in his tank before, Lolli suffered from poisoning of some kind (maybe nitrite?) and passed...

I'm sorry I can't help more. I hope someone more experienced in disease comes along to save the day, and hopefully Tony. Good luck friend

P.S. forgot to mention that Lolli couldn't swim well anymore. Not swim bladder related, just lopsided...

 

My black line rasbora has gotten very sick seemingly overnight.
Had a new fish I introduced die, so I think it might be parasites? Tony, the rasbora has been slowly developing some red gills and spots, but it got tremendously worse today, he’s now swimming upside down and looks very pale.

PH- 8.2
Nitrates -40
Nitrite- 0
Ammonia - .25

20 gal
25% water changes weekly
my tank is not doing good right now and I don’t know why, I think it’s overstocked and I want to move fish into my 35 gallon. I’m afraid of potential disease transfer though. I really don’t want to loose anymore fish and would like help saving this fish.

Update- scales falling off!? Do you think I should just euthanize him at this point? If there’s any chance of saving him I want to try. This fish has been healthy for two years with me, I don’t know what happened

Update- I decided to euthanize him (clove oil) as he was not looking like he could swim at all or recover. I still don’t know exactly what it was, thinking “red pest,” but don’t know.

 

Update- I decided to euthanize him (clove oil)

I'm so sorry friend...at least we know Tony, which is the best name for a fish, had an amazing life! You did everything you could and in my opinion, you did amazingly well

 

I'm so sorry friend...at least we know Tony, which is the best name for a fish, had an amazing life! You did everything you could and in my opinion, you did amazingly well

Thank you so much, you are so kind! This means a lot. I get really attached to my fish and just want to see them thrive! Thank you for the kind words