pretty good game there are just a few minor adjustments that need to be made imo, im gonna nitpick so bear with me please:
1.as other people said the knife attack can be improved
2.the player's or fish's collider is too big (small fish can attack from far away which makes it feel unfair)
3.damage is in decimal, would probably be better to multiply the player health by 100 and fish damage by 100 and just make the damage in Integer
4.the enemies damage text and player's damage text are nearly the same color which makes it hard to tell apart and a bit confusing at times
these are just some little faults and overall its a good game and you did a very good job for just a week!