Ummm... so not everyone know this, easiest place to find the fish on The Island map is by going to the vegetarian dino island and searching the shores, it's gonna be dangerous, i will try to get more information on how deep they usually are
(Mobile) The friendliest creature in the ocean and possibly the entire island. It will never attack you, even if you hit it repeatedly and have ammonite rage status on you. It might not seem cute to you, but you're a true monster if you kill them on purpose.
Came upon this creature without any prior planning, had some spare prime meat so I thought why not? Immediately after taming it, 2 megalodons, a male and female, swam up to the shore and killed it before I could do anything to help. Proper planning like having a saddle ready and some kind of water inclosure already made for the creature is probably your best chance of keeping it alive.
So I had 2 icthys and it was amazing, they didn’t make anything aggro,but 2 Brontie fell in the water and killed them accidently. So I had to get a new one. It took ages but I eventually tamed one. But as soon as it was tamed 2 megs attacked it. It barely survived, but out when I was taking another icthy with it all the megs and mantas started to attack it. I’m so confused the other ones didn’t make anything aggro
Go to herbivore island (The island) at the right bottom. Go to map if unsure. Look around and you should find some itchyosaurus. But be careful, in the water they look like sharks, don’t mistaken them as sharks they have a pointed snout. Like if you found it helpful! :)