Flowerhorn fish belly keeps on becoming bloated with water?

[Ems]

Have you tested your water?

No

If I did not test my water...

...I recognize that I will likely be asked to do a test, and that water tests are critical for solving freshwater health problems.

Do you do water changes?

Yes

What percentage of water do you change?

11-20%

How frequently do you change your water?

Every week

If I do not change my water...

...I recognize that I will likely be recommended to do a water change, and water changes are critical for preventing future freshwater health problems.

Hello I would like to ask about this condition with my flowerhorn. He does not have any problems aside from noticeable bloating of his belly, and only the left side specifically. I know it is with water because I applied some gentle pressure on said bloated belly a few times now and notice liquid similar to water that comes out of him. After that his stomach usually seems normal but will eventually become bloated again, seemingly due to the water accumulating. He becomes noticeably less aggressive when his stomach is bloated, but after trying to get the water out he comes back to his usual aggressive self.

I want to ask if anyone know the condition my flowerhorn is having? Or may I ask for suggestions on what to do?