I recommend erheir raw prime, or raw prime fish meat.
I tamed mine with raw prime fish meat only, no soothing balm. I actually was pretty lucky, because a basilo spawned next to a leed, and a leed spawns next to a basilo. So I took all the leed's raw prime fish meat, and put it in my Bary. I fed it constantly, aware of oxygen.
Finally, I tamed it and named it Silo. Saddles are suprisingly unexpensive. These also spawn by Herbivore Island. Along with leeds. So I you see a basilo, look for a leed if you a trying to find one. Everytime I see a basilo, I see a leed. Be careful! When you feed it the mantas attack. Recommened mount, baryonx. Baryonx will stun the mantas, and you will be able to feed the basilo while on baryonx too. They come in variants of dark blue, or a pink, magenta color. They have a good bit of health, and do not aggro on you when you get close to it. Have fun with your basilo, if you read this. Goodbye -TinaZ
Ride dolphin or manta, water creature won't attack you while riding a water dino, then go near basilo feed it, Don't unride or you'll see your self dying, put food on your hot bar then click it when near basilo u can feed basilo without unriding. Up! So no noobs will be eaten by manta or megalodon lol
Basilosaurus are found in the oceans surrounding herbivore Island
Basilosaurus are passive tames that arent aggressive towards you at all and they are carnivores so feed them meat.
Basilosaurus are surrounded by mantas and they will attack you when you feed or attack the Basilosaurus, there are plesiosaurs,megalodons,leedsicthis and tusothuthis where the Basilosaurus are,
Basilosaurus are slow so you're underwater mount can keep up with it.
Abilities when tamed:
Basilosaurus are immune to jellyfish stings and eel shocks and cannot be grabbed by squid, they produce oil in there inventory but it spoils, they regenerate health fast near the surrface, they can shoot rainbows out of their blowhole using one of their attacks
Disabilities when tamed:
Basilosaurus lose health when they are in deep water
Okay, so I saw one in a river opening on Crystal Isles. I thought the mantas attack you as soon as you go near. So I slowly approached the tail near the river bank. The mantas didn’t agro on me, I thought I was just far enough away. No. Oh no no no noooo. It turns out the mantas ATTACK the second you feed it. Please don’t do what I did haha
There's a river on the west end of the redwoods that's considered ocean so they'll spawn in it. Just gate off each end to trap the basil, kill whatever's in the water, and you don't even need a water tame.