i'm a wee bit worried about my oldest rat (1yr old) custard.

his fur (or fluff as i call it) looks very tatty his eyes etc look ok and hes not lathargic no change in his behaviour aall he seems happy and healthy.

is this cause for worry or am i just being silly
or is it just a case that rats do mault hence his scruffy appearence???

if its nothing to worry about can i do anything to bring the condition of his coat back?