With 0.01 taming, level 9999, and with cooked fish meat, this takes 93 years to tame

The best way is to use the Tek skiff which you unlock after the boss fight(like the saddle) and have cannons mounted on it. Probably easier with multiple people

Use a bloodstalker and a rocket launcher, jump around to its face and shoot it with rockets until it knocks out. Jump off the stalker and land on the whale to quickly feed it.

To tame these, you have to learn Whãle from, Dory.
Ahem.
"Ooo Ooo" "OoWaoooo" "Huff. Huff."

"Incomprehensible Whãle Noises"

Then Wåla! It is tamed!

Don't use mek because the astrocetus takes first the torpor and then the damage. The effectiveness will go down.
We tamed a 130 with mek and Kibble and get a 136 -.-
I think the stronger the weapon the more you loose the effectiveness, so the "best" way is to knock out with rocket launcher.
It's the same effect with rock elementals.
Wildcard should repair that.

Get a mek,put the rocket launcher attachment on it,then shoot at its head

You can actually knock it out with a Mek Cannon if you do not have the Tek skiff.

Obtain a Tek replicator from tier 3 crates in the shop, and craft the Mek from the engram

Mek cannon one shot KOs any level.

I used a ufo with a canon didn't take long to knock out and was able to do solo

Become a space pirate load a skiff with cannons aim for the head and knock it out easier with 2-4 people.

Tranqable with rockets so use that if its cheaper

You need to use a mek to get the work done, the first thing you need to do is let it agrrow on you so shoot it with a dart or something then use use the mek to shoot rockets ate his head like the titanosaur method

Its a knockout tame, get a cannon and shoot it's face

Pretending to molest it while it’s unconscious will not only lower taming effectiveness, by it also didn’t give consent so you’ll go to jail.

Genesis pics just came out I can see them now!

Use the skiff with cannons on the front of it, aim for the head (front on) can be done solo but much easier with 2 or even 3 and doesn’t take much to knockout.

To KO it you have to use the turrets on the TEK Hover-Skiff then you use exceptional kibble or meat to tame.

You can use a rocket launcher to knock it out

Using a Mel Cannon destroys the gaming effectiveness so use rockets or cannon balls. ~Whoo1

Hover Skiff makes this easier but isn’t necessary! They aggro very easily to player structures, I got my first one mad at a stone dino gate on the ground. Once it’s stuck to the gate, put a couple cannons down (this is important- they’ll run away faster than 1 cannon in most cases) and put em to sleep. 2-3 cannons and 3-4 cannonballs.