I loved the cute visuals and the animations of the penguin were very nice and the general aesthetic was very pleasing to look at! The particle effect of he snow added some nice visual interest as well as the semi pixel art "wobble" and "bounce" animations and the black outline on the player.
The sound effects were also nice and added to the experience too and the general controls felt fine tuned and responsive to use!
I'm not sure how the game tried to fit the theme really worked as if the fish were replaced with some sort of "slow-potion" sprite the game would work perfectly fine as they are essentially another type of obstacle. But the theme was evidently there though! The camera could have done with being zoomed out a bit more too just so you can prepare a bit more for upcoming jumps, that might just be personal preference though.... or maybe the camera could zoom out more the more you die?
Overall, this game was very addictive and played really well, I'd definitely recommend giving it a go as the gameplay is extremely fun!