u/Brief-Supermarket-11

My daughters pet guppy of approx 2 years lives by himself in a 28lt well established good parameter tank. Three days ago started acting weird hiding, rapid breathing but eating. I changed water checked parameters all good, he then goes and hides and i havent seen him more than a day so I assume the worst about him next thing I know the guy comes out has a snack and acts normal then disappears again. I dont understand is he unwell or just old?

Ps. Sorry for bad photo had to zoom im also dirty tank