six-line wrasse illness

Hi, this is my first post here but unfortunately it's not under good circumstances. I have a 20 gallon aquarium with 2 damsel fish and a six-line wrasse along with many crabs. I've had the six-line for nearly 3 years and the damsels for almost 4 years.

The damsels are doing fine still, however the six-line has be come increasingly lethargic and seems to be breathing heavily with his mouth wide open. I talked with my local fish dealer and they suggested that it was perhaps he had something stuck in his throat since he had defecated recently (Monday). He's also not eating, I've tried pellets, flakes, and frozen brine shrimp.

I've kept an eye on him for a couple of days and there is abdominal swelling that appears to be getting worse. I've attached a few pictures in case anyone has run into this before.

 

Pregnant? looked like my Fw molly when she was about to give birth.

 

Welcome to 3reef,

I wish I could offer more assistance, perhaps this link will provide some help or guidance.

Marine Fish Diseases and Parasites