Bulging Stomach?

Anyone know how can I fix this? Looks like an infection..... I guess this is my first time having a SR...bought if off some guy that had it for a year now. This seller had his ph above 7.5 ( threw salt everytime he did water change. didn't think the bulging stomach would be a defect....thought is was starving. Any expert out there who can assist me or cure this. Sorry no pix...still searchin for a great digital camera.