strange problem

Hi to everybody!

Today something strange happened!

I took over a Golden Arrowana from my brother some months ago because he didn't eat.

After treating him well, he started to eat very fast again and became a good fellow in our home.

From the beginning I took over the Arrowana, it was clear he will need a bigger Aquarium than he has now (300) Liter. The Arrowana is about 30 cm long.

So a month ago I bought a 1000 Liter Aquarium. I set it up and let it run for a month. Also I put some Jewel Chilid and Buttikoferi inside to let the filter start to work.

Today was the big day: First I fed the Arowana before putting him into his new home. After that came the moment.

He was in. I watched quiet closly to see how he will interact with the buttikoferi ( they can be quiet mean). But it came out I have to worry about the Butti's more than the Arrowana.

The Arrowana was obvious very comfortable in his new home. And started very soon to catch after the chilid's.

Swimming arround and being very happy. I wanted to have a cigarette break after my observation. 4 minutes, I came back and I couldn't believe what I see.

The Arrowana is swimming in a 45degree angle heads down. Trying to put him straight, but it was the back which pulled him up again. It looked like the back was filled with air and didn't want him to go under water!!!

What is that!! What happened!!!
After a little research, escpecially here in this forum, I cam e to the conclusion, that he must hurt himself in the 4 minutes I was away, also I saw him getting air from the surface. But so suddenly???

For the moment I brought him back to the old aquarium and I filled just that much water that he can breath (water level=back level) this way he is not turning arround (bottum's up). in the last hour he was fighting quiet strong, so he became so tired that I needed to do this step (even I knew it is stress again for him). No he became relaxt and he can regenarate!

Does anyone know what this is? Does anyone have an idea how to help this fish?

Thank you very much!

Mark