Protein expression of hypoxia-inducible factor 1-alpha (HIF-1α) in spot (Leiostomus xanthurus) exposed to constant and diel-cycling hypoxia

► This is the first study examining HIF-1α protein expression in fish exposed to constant versus cyclic hypoxia. ► Diel-cycling hypoxia produced more expression of HIF-1α to constant hypoxia over three days during all trials. ► We conclude that overnight hypoxia from diel-cycling systems is detectable using HIF-1α protein.