When a timid reef fish, discovers the world is about to be destroyed by a single ordinary human, he must find a way to stop them, and survive a treacherous journey to the surface world.

There’s a few bits in this where I struggle to suspend my disbelief. I find it hard to believe that a single ordinary human can destroy the world. Without an explanation, I can’t see how. Knowing that there’s a plan for the fish to be aware of suggests the human is knowingly doing something to destroy the world. WHY??? This makes no sense to me.

I also struggle to see how a fish is supposed to survive on land and stop a person doing anything. How did the fish even become aware of this? Did this human tell this fish his dastardly plan???

I have way more questions than I should and I feel like the plot is so unbelievable (based on the information currently available in this logline) that I just dismiss the idea. It could be that the information in the logline is too vague, so you may need more specificity to clear up obvious and problematic questions the reader will have.

Hope this helps.