My Favourite and Easiest way to get a Basilosauros:
Get icthy. Pump health and speed. Get prime meat or kibble or whatever you have (preferably kibble, prime meat or mutton) and put it in last slot. Feed to Basilosauros, hop onto icthy really quick, then bait all the mantas as far away from the Basilosauros as possible. Most will not go back for Basilosauros. Rinse and repeat with new mantas he picks up along the way, boom easy Basilosauros.
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
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
Pro Tip: Basi’s won’t spawn with a whole gang of mantas on Gen 1 map, making it much easier to tame. You also have increased oxygen and swim speed in Gen 1’s Ocean Biome so you won’t need scuba gear and you can outswim Megalodons easily.