This was a fun little platformer, I love penguins so I clicked through to this out of the blue xD
The core mechanics were good, although I seemed to die a lot to some of my spacebar pushes not registering quickly, perhaps that was just me! I also spent a confused couple of minutes trying to work out why the <> buttons didn't do anything before finally realising you meant the arrow keys - might be something to label a touch more clearly in game in the future, but it's in the description so I can't fault that! My own common sense working against me there, really...
I liked how the fish played with the instinct to collect collectables, and made you larger so obstacles were harder to clear, and how the speed of the levels made dying almost an act of scouting ahead (failure is progress!) even if my memory is pants enough that I wasn't benefitting from it much.
Ultimately I quit out around Level 6 because I was really starting to feel the gameplay repetition, but I'm not a big platformer player so I wouldn't take that as a negative! The art and music worked well together, and the whole game has an air of polish which is quite impressive for the timeframe, on the whole, nIce Job!