Big tummy or Short body?

Hey guys...ive a short body green terror...recently transfered it to my 422...it grew bigger but appetite started to decrease....some level of stress too because of my IT...but now i dont see any physical fighting...

its tummy is currently very very big...to the extend the scale LOOKS like dropsy ...but its still closely stuck to the body....

i was wondering if this is normal for a short body fish...or issit internal parasite....or constipation....all other fishes in the tank are healthy (pearl aro...clownloaches...discus...it..)

any preventative medication i should use like epsom salt or anything? can any bro advise the dosage and medication to use? my tank holds around 384 litres of water...THANKS IN ADVANCE!