Found the tidepup on astreos on the new island if needed look on wikily for location info but idk if they r rare but can be found, i brought it to my base into a trap brought some dinos like otter and dodo and tamed it that way

If you wanna find some quick, just use the NW spawn for ocean biome. Head SE after you teleport. You'll find plenty in and around the cove there.

Update on my elusive comment they are in fact NOT rare I found like 20 in my first 5 minutes