Use the speed variable to control the speed of the fish.
DO NOT ADD TO AE STUDIOS! I literally thought of everything. I allowed the fish to turn around at the edge while still using only one of the "change x by" brick instead of the "move steps" brick. I used a speed variable that allowed you to control the speed of the fish. I used a variable that stopped the fish from turning around after it had turned around once at that edge. If you want to see what I did, then click "see inside". I labeled everything I did with notes. And trust me- compared to what I usually do, this is baby stuff. Don't believe I can top this? Then check out some of my projects.