If breeding on Lost Isles head to 42.5 lat 17.8 lon. you can breed in the bottom of that mini trench thing. Area is too hot to hatch in but you can just build a mini hut with an incubator and gen at the bottom. Set incubator to -5 that's my sweet spot.afterwards cryo it up ride to surface and imprint.

Preparation is key to not spending 10+ plus hours like I did the first time trying to tame. First setup behemoth gates each with doors in the shallow water as a trap. I'd say 5 to be safe but can be done with just 2. Allow space between behemoth gates big enough for a mosa to fit tightly between. Make sure you have a speargun or crossbow to kill coels and sabersalmon since they spawn and eat the fish swarm. Go ahead and trap your megachalon. You dont need a roof on your trap since the creature gets stuck in the doors. Here's where things change depending on solo tame or duo taming. You must be within a few blocks for it to maintain in taming. So if you have a partner, choose who will stay with the megachalon and who will be pulling swarms to the tame. Put poop in your last slot to maintain aggro of swarm. You most likely will need multiple swarms. If doing solo, get at least 4 swarms just out of agro of megachalon before starting and then kite each as needed to the tame.

On ark ascended gen one the water boome changed a bit and so did the method to tame these. The sabertooth salmon and coels that spawn will no longer hit the megachelon resetting the tame making it a bit easier as you only have to make sure other wild sea creatures don't attack it. The downside of the new changes are the new water physics. The surface of gen one has a new mechanic that pulls you up, the turtle likes to get stuck on the surface of the water and will cause the parakeet fish school to explode upon coming in contact with the surface. The best way to tame these is to lure the megachelon to deep water instead of luring the fish to the turtle which usually resides in shallow waters. They like to swim up so starting the process in deeper water ensures it goes much more smoothly but can be a pain to lure the turtle as they're slow. Other than that just find a parakeet school and let it clean the turtle while defending the school of fish from the other fish that spawn in. It's a long process, I've heard on 1x it's 30 minutes regardless of level. Just be sure not to accidently hit the turtle while taming and it goes a lot faster than you'd imagine.

Fun fact use it in the lunar biome to gather stone, crystal, wood thatch fiber like crazy from lunar bushes, go to the Arctic to get sap from trees, go to ocean to get silk and plant y seeds and big biome for plant x from those narco plants. Volcano needs testing to see what it's good for. Enjoy building stone behe gates in lunar :)

You can build on there back without saddle and you can stand on there back underwater DO NOT cryo these guys if you build on there back if you wanna keep the building you will loose all of it platform or not .

Press the sky so people don’t make the same mistake as I did 💔

If you decide to kill the megachelon then stand on the back of it and start attacking this will force them to stay at the surface and they can’t attack you. If you have a tame I suggest a blood stalker because if you attack and move left and right you can actually steer the thing it’s fun.