Help with wierd P. volitans

[petrol]

Hello, and sorry for my English.

Have a weird volitans..

My well fead adult P. volitans startet a fed days ago to swim above the surfaca!!

He(?) looking like a crocodile with the eys and fins above the surfase.

Hes not interested of any food! Hes normally got fresh marine fishes (coold water fishes).

Cant see any desises ore something different on the fish.
My other fishes are like normal.

Best regards
Petter