No restrictions on shellfish in the Muslim faith. But no carniverous animals, that means aligators are out.
I worked for a place a few years, just after I'd got out of school, that supplied food and sundry items, hardware, etc., to offshore rigs and ships. I was a ship chandler, the guy who met the ships when they arrived at port to solicit their orders, or went out to the rigs. The result is a million stories I could tell about those days, plus since then
Lord Jim has always been one of my favorite novels.
Anyway, one of our clients was Mobil Marine, their international fleet, which ran lightering tankers up the Neches River from Point X out in the Gulf, to their refinery here. The officers were always German or English, the crews mostly Indian Muslims. We had specific instructions on some of the food items, the sheep and chickens had to be 'Mohammedan killed' (MK), in other words bled from the jugular. An imam was to oversee this, and bless the meat before we shipped it. Only, I didn't know any imams, and our operations guy made a perfunctory attempt to locate one, or any slaughterhouse in the area who would do this sort of thing for a decent price. He found neither. So we ended up just sending them the same stuff we sent everyone else.
This was the early 1980's, not too long after the Iran hostage thing, and most people around here didn't know much about Islam, and what they knew wasn't necessarily to their liking. Even so, I felt kind of bad about sending these guys officially unblessed and, for all I knew, tainted meat. They had trusted me, and it was their religion, after all. I guess our operations manager felt a pang of guilt, too. One day, in a solemn ceremony on the loading dock, he appointed me an imam (on what authority, I am not sure.) I was directed to compose a short prayer to bless the animals with. After that, every time a shipment was going out, I would be called to the shipping dock, and as the warehouse guys stood and shuffled solemnly, I would bless the meat, then pull down the truck door and lock and seal it, and send it on its way.
We used to laugh about it at the time, but I still sometimes wonder if there were a lot of guys trapped in the Muslim version of purgatory, if they have one, all because of our contretemps with their food orders.
I hope not. That is a pretty heavy metaphysical debt, and I don't know that I have done enough on the positive side over the years to balance it out.