Darting/hiding Betta

[Alz1992]

My betta hides in an ornamental skull quite a lot, and it rarely comes out. when it does, it usually stays on the gravel or seems to run into things slowly and dart away. i caught it earlier on a plant doing what looked like a scratching motion against the leaf. only for around a second though before bolting off.
the other fish in the tank seem fine, whats wrong with the betta?

no signs of deterioration, no white spots, fins look fine, water stats are fine.

 

[loraxchick]

Shine a light on him in a darkened room and look for rusty/ reddish specks/ dusting on the fish. He may have velvet which is parasitic infection. Easily cured with tank blackout for few days.