Ok i think it has dropsy
And salt is not the method of treatment
Let me attach what I’ve read
Dropsy
Cause:
Caused due to bacterial infection of your fish internal organs.
Poor water quality
Overcrowding and stress can cause this disease
Symptoms:
You will get to see excess body fluid which builds up inside the fish.
Eyes and Scales are swollen more than normal.
Will stop eating food.
The fish may appear bloated.
Treatment:
Commercial treatment is available at your local fish store.
Act as soon as possible since this disease can kill your fish.
Never use aquarium salt while treating dropsy, this will kill your fish in short time.
You will need to use Tetracyclin, Maracyn, Kanacyn or broad-spectrum antibiotic foods, commercially prepared treatment available at your fish store.
Prevention:
Need to do lots of water change.
You will need to avoid the cross tank contamination.
Always need to quarantine doubtful looking fish for 3 to 4 weeks.
I didn’t write this not trying t take any credit just trying to share what I found