Bring good armor and a healthy tame, the fish can dish out alot of damage and standing next to one for only a second could mean death, the fish have a low aggro radius so leading them can be tedious. Once you have successfully made the fish follow the turtle (the fish will stick very close to the turtles butt) have one person on foot follow the turtle around and another on a bary farther away to kill sharks. Side note all turtles tame at the same rate regardless of the lvl from what I've seen.
They have patched the render range range so ignore any tips that say to leave render as it will no longer. Guess I’m stuck with the turtles I have, I’ve spent three hours trying to take one of these things and had it walk out of the water which reset it taming! It was at 80% that time. Never got it above 20 after that. What he for the saber tooth salmon that spawn to kill the swarm if they bite the turtle it resets to zero and you start over. Extremely frustrating way to tame a creature. I would like to beat whoever came up with this idea.