Hi all,

Need your help as this is something I observe long ago whenever I get some fish from outside.

After settle down for a week, some fish start coming some syndrome of gasping some air (head jump out of water) while swimming in circular mode.

When I observe further, he has no sign of parasite, diet strictly on pellet, change water every 2 days.

What would be the likely cause?

At this point I only medicate with some salt and Aquari-Sol from AP.

Any advice from you guys.

Need to save this guy as I want to preserve his trait before he is gone.

If he doesn't have parasites, the only thing I can think of he is having a reaction to the change in the water.
If you observe this primarily ofter you water change him, then this is for sure what might be the issue.
They could also be having a poor adjustment from being outside to being in a more cnfined space, much like you see zoo animals in certain areas that pace back and forth.
The gasping and the jumping out the water could be stress.
These are just some thoughts I have on what could be the issue with your fish..

If it is the water, dechlorinator would help, or using the water from outside, or very aged water..
If it is the change in his surroundings, try giving him more room, or covering his tank, so he is not seeing anything, like carding him from the waord.
The good thing is, if you don't care of the cause, and you just want a cure, you can try dechlor, giving him more room, covering his tank, all at the same time.
I hope your fish gets better...