Backyard Aquaponics
A place to discuss aquaponics

Hi,

I started noticing my large Koi very lethargic and head down tail up swimming sometimes just 2 week ago in my pond. I shifted him to my home aquarium to check what's wrong with him. I saw no white spots and no red streaks or any other spot. So I applied Rid All Medicine with 2 PPT salt. And I saw improvement in just 2 days. Koi became fine in 7 days.

Yesterday I saw one of my small koi very dull and not swimming not eating. He was just bottom sitting. I moved him to my home aquarium as well where I have salt and medicine in water. And to my surprise I see improvement in just a day.

Today I noticed another small Koi missing in my pond and after searching for him I found him dead hiding in a corner. He too was acting dull and lethargic for a few days.

I saw no white spots or no red spots on him either.

Why my fish are becoming ill and dying?

I have white Koi fish too and they are all looking fine eating like a monster. Other two smaller koi are also swimming and eating normal.

I see white fungus on hydroton of my NFT plastic cups.

Ammonia and Nitrites are 0 and Nitrates are between 40 - 80 PPM.

What's wrong here?

I'm not sure what your temps are but if the water's getting really warm you could have low oxygen levels causing problems and stressing the fish out so they get sick more often. Wide temperature fluctuations will cause problems by themselves. Take a look at your pH as well.

And feed, has it changed at all lately?

I'd look at oxygen first too though.