i have a betta that keeps hiding in the filter and i cant find out how hes getting in there!,must point out the filter is an internal compact bio filter with no gaps but has a lid which comes off easily but not so easy for a fish,ive been watching my betta now for about 4-5 days and if i cant find him, gauranted hes in the filter,after watching him there is no fish having a problem with him fighting etc,hes eating,acting normally except for the hiding but he seems quite content,before your having bad thoughts like omg hes in the filter hes 100% perfectly safe, can anybody tell me whys hes doing this or some advice why hes doing this?