It is a mystery.
I lost two lf albino bn plecos in the first two weeks. I tried everything to save them. There were several theories, and I will list what they said in case it helps you.
One theory was that there was not enough oxygen. I got a piece of
driftwood with a plant on it and a air stick. He died.
The next theory was that I had the temp too high. It was set to 80, I lowered it to 78. He died.
My parameters were amonia 0,
nitrite 0, and
nitrate 20.
Now I am on my third one, and he has made it for over a month. He is very hungry all of the time, and he is growing like crazy. I am very happy.
Hope that gives you some ideas.
