The lighting looks really good! I love the idea of a fish dungeon!
The range of the sword felt too short, and the stamina replenished too slow. I also felt like having your life refill slowly would have made for a more fun experience. Maybe for an easy mode? I played without looking at the map, and found fish before I found the sword on my first play through, so maybe prevent that or start with the sword? After looking at the map I realized you basically need it. I didn't know what the I's were and the graphics for the arrows were very hard to figure out. I kinda thought I'd be able to shoot as soon as I found the bow. I never found a key or the hammer, and I was trying to figure out how to open the closed passages to no avail. The magenta fish felt OP, so I just ran from it. Getting corned by fish, with no stamina felt bad. I wasn't sure what the green floor was for. Just for variation perhaps? At first I thought maybe it hurt you.
Over all the game was good! I could tell a lot of effort went into it. I was glad that when I accidentally used the health potion with full health that it didn't get used, though the sfx did trigger. Perhaps a different SFX could be used there? Awesome job given the limitations!