I recently got two oscars for my aquarium and one passed away after an ich infection and recently I found a pink sack underneath my fish and I believe it is due to constipation.I am wondering what I can do to help my Oscar.
*Water PH is 7
*Temoerature us normal
*Low ammonia and nitrate
Difficult to determine from the pic, but I believe your diagnosis is likely correct, "Constipation". The protrusion is called a "Prolapse". There's really nothing do but let things work it's way out. Hold off feeding for a few days. Some reccomend a fifteen minute Epsom salt bath, done in a hospital tank. I've never tried that, but plenty of info on line about the proportion ratio between Epsom salt & water.