“…Since the OCLTT hypothesis has not yet been shown universally to determine the upper temperature tolerance limits of fish, it is possible that alternative mechanisms could be involved, including disruption of neural function ( Ern et al., 2015 ; Jutfelt et al., 2019 ; Andreassen et al., 2022 ), impairment of cell membranes ( Bowler, 2018 ), enzyme denaturation ( Somero and Dahlhoff, 2008 ), ion imbalances (particularly of potassium) ( O’Sullivan et al., 2017 ; Zimmer et al., 2024 ) and failure of critical organs (e.g. heart or brain) ( Sidhu et al., 2014 ; Jørgensen et al., 2017 ; Andreassen et al., 2022 ; Schwieterman et al., 2023 ). Indeed, all of the above processes could be involved in determining the acute temperature tolerance of fish ( Ern et al., 2023 ), demonstrating the complexity of predicting how environmental changes may impact thermal limits.…”