▁t aut og ▁T aut oga ▁on itis , ▁become ▁active ▁day ▁and ▁night ▁during ▁migration . ▁In ▁the ▁Moz amb ique ▁til ap ia , ▁sleep ▁has ▁been ▁observed ▁in ▁adult s , ▁but ▁not ▁in ▁ju ven iles . ▁ ▁Some ▁species ▁may ▁be ▁variable ▁in ▁the ▁ph asing ▁of ▁their ▁daily ▁activity / in activity ▁periods , ▁and ▁thus ▁pres umably ▁of ▁their ▁sleep . ▁Within ▁the ▁same ▁labor atory ▁populations ▁of ▁gold fish , ▁some ▁individuals ▁may ▁be ▁sp ont ane ously ▁di urn al ▁while ▁others ▁are ▁no ct urn al . ▁Gold fish ▁can ▁also ▁be ▁di urn al ▁if ▁food ▁is ▁more ▁available ▁by ▁day , ▁or ▁no ct urn al ▁if ▁food ▁is ▁available ▁at ▁night . ▁Sal mon ▁are ▁mostly ▁di urn al ▁when ▁temperature ▁is ▁high , ▁but ▁become ▁more ▁no ct urn al ▁if ▁temperature ▁pl umm ets . ▁At ▁high ▁lat itudes , ▁capt ive ▁bur bot , ▁sc ul pin ▁and ▁brown ▁b ull head ▁are ▁no ct urn al ▁in ▁summer ▁but ▁become ▁di urn al ▁under ▁the ▁short ▁phot oper iod ▁of ▁the ▁Ar ctic ▁winter . ▁In ▁capt ivity , ▁white ▁su cker ▁Cat ost om us ▁comm erson ii ▁are ▁di urn al ▁when ▁living ▁in ▁a ▁sho al ▁but ▁no ct urn al ▁when ▁living ▁alone . ▁ ▁References ▁▁ ▁Category : S leep ▁Category : I ch thy ology ▁Category : S leep ▁phys i ology <0x0A> </s> ▁Pod ol any ▁may ▁refer ▁to