Moonbeam Swollen Stomach

Just a thought on looking at your photos and based on my own experience. When I transferred my substrate from gravel to sand because my goldfish had a habit of swallowing and choking on the gravel, I ended up with another problem - he foraged and ingested sand in the process. He developed a pouch on his side ie a swollen section internally but which could be seen quite easily when looking at him. When he pooed, it came out extremely thick (must have been painful for him to pass) like Udon noodles rather than standard string, and grains of sand were very visible in it. Is there any possibility that this could be happening in Moonbeam's case? Keep an eye on his poo / him poo-ing and it might help work out if indeed this is what's happening. If so, it may be that you need to change the substrate - in my case, I opted for a bare-bottom tank after the repeated problems with gravel and sand.

I see what you mean from the photos, and it does look to be more on one side.

I have read of bettas with tumours causing swelling on one side; I had a betta years ago with swelling on one side (much worse than Moonbeam) which turned out to be full of yellow goo, but I have no idea what that was caused by.

There are just so many things it could be, and not all of them curable 

Hi
I do use root tabs but they are right under the sand , I could have dislodged when hoovering and it gone in the water I suppose .
Haven't put any in a while though 😩