my rat chuchip has black eyes but when looking at something he holds still and moves his head back and forth like a pink or ruby eyed rat would, any idea why?
Rats that sway their heads back and forth do so because they are trying to compensate for poor eyesight. Pink and ruby eyed rats do it more often because lighter coloured eyes are more likely to be associated with poor eyesight but if a black eyed rat has poor eyesight it may do the same thing to compensate. Rats don't have great eyesight to begin with so it's not something to be overly concerned about.
Is part of his room dimly lit? My black-eyed kiddos only head sway during the day when the lights are all off and the only light is coming from the window, the whole room is significanly darker.