Build a 3x3 trap on a plesio patform standing on pillars as far back and high as you can go.

Dunkleo and sharks won't be able to attack plesio from inside. Trank risk free. Swim away when it fell asleep. Similar to quetz, just no need to have back wall removed/placed to catch it, the will swim thru the wall if you move. Once inside , just stop moving and it's trapped.

More Dunkleosteus Taming & KO Tips