I was new to the mosa taming until last night when I found a 140. Just stay above the depth limit or trap them into a rock. I starved my mosa because the last update released the eels and you don't want to lose taming efficiency.
Center tip: as they have added the mosa to the center I've found the easiest way to knock one out is find one close to the bubbles get its Agro and swim in the bubble the mosa will get stuck and it can't hit you. Also this gives you unlimited oxygen and sanctuary from being attacked by anything else. ðŸ¤˜ðŸ¼