could someone identify this disease?

[Hydropumped]

My foxface seems to be in perfect health condition. Only thing is, while it's swimming, it slowly falls to the sandbed and kindda lies on it's belly and sideways. When I tap the glass, it immedieatly swims away. It seems like he's trying extra hard to swim with his fins. Other than that, he has been eating fine and no other inhabitants have picked on him. I've had him for about 2 months now and hes been doing it since the beginning.

 

[RWD]

up^

 

[Ben1]

Possible internal fungus infection, Just my guess, Id ask David Morh if he cant help you no one can.