Everybody is a genius.
But if you judge a fish by its ability to climb a tree, it will live its whole life believing it is stupid.
-Albert Einstein
But think again. There's a certain fish that can climb a tree. They're called climbing perch.
Climbing Perch (also called Climbing Gourami and Walking Fish), a freshwater fish that comes out of the water to breathe air for hours at a time. The fish cannot derive enough oxygen from water because it has very small gills and generally lives in oxygen-poor water. In a cavity above its gills is a respiratory organ that enables the fish to absorb oxygen from the air. The fish is frequently observed moving over land from one body of water to another; it moves by flexing its tail and using its fins as props. It has also been seen climbing sloping tree trunks. It feeds on crustaceans, insects, and vegetation.
So... there really is a fish that can climb trees.
However, if the fish is not a climbing perch, please just leave it to swim in the water and let it be the best as it can be.