I haven't encountered these yet and this is just a maybe but i think maybe you could use a pteranodon or some other flyer that can pick up animals, you can make a 1x1 hut without a roof and drop it there, and make it be right next to a water source with fish to make the process quicker. If the water source is shallow enough you could use something like a trike or a baryonyx to insta-kill a bunch of fish, and I'd probably recommend saber-tooth salmon since coelocanths give too little taming effectiveness and i don't think piranhas are worth the hassle.

Like i said, all of this is a big maybe, and maybe it doesn't work

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