I Am Fish

EDIT 09-DEC-2021: In summation, no clue wtf gives you 5 stars. All the comments below show that any notion I had of what counts as a 5 star run goes out the window. So..... Do it fast and try not to die. Horrible solution, but it seems the grading for these levels is just as bad....

As far as I can tell, the most important thing for a 5 star run is not dying (or dying very few times, depending on the level). Bread pieces DO NOT count towards stars. I played level 1-1 a few times, and ended up getting a run of 3:49 with no deaths, and got a 5 star. My quickest time prior to that was 4:50 with 1 death, and it came out to be 4 stars. Counterstriker8 in the comments below had a final time of 4:59 with 2 deaths and still got 5 stars. So........ no consistent structure to this as far as I can tell.

Not sure what the exact criteria is, but focus on no deaths before going for speed. I will update this solution once I get more info.

For this achievement, you just need to beat goldfish level 1. I did it while learning the game, and I died once, but still got 5 stars. If you need some assistance, check out the video. Good luck!