Scientists have found out that fish can do math. Fish can do simple addition or subtraction with answers between 1 & 5
Fish were trained to recognize that yellow meant to add one and blue meant to subtracting one. So if the fish were shown three blue objects, they would add one and find a treat by swimming through a gate marked with four shapes.
Likewise, if they were shown 3 yellow shapes, they would find the treat through the gate with 2 yellow shapes.
The fish were right between 69% & 94% of the time.