A very easy tame if you're exp and know what ur doing

Grab an Itchy, also get some Toxic Arrows

Find ur dunkle and start shooting it w the arrows, make sure that u dont dismount ur itchy accidentally, the dunkle wont attack you if u are on the Itchy

When u knock it out feed it some raw meat and get some Bio Toxin/Narcotics

If u can use a Balm, it is more easy

Just wait and voila, underwater anky

Hope this helped :)