Halibut would probably work too but cod is generally less expensive.

Of those three, the snapper is likely to be the least expensive. Does the recipe call for calamari or squid too?
With all that seafood, Cioppino is an expensive meal to prepare, but oh so good!

Yeah, the recipe ingredients are looking like $35, but it's a once-a-year treat. I'm not using calamari or scungili, but will add three small lobster tails.

Thanks for your suggestion.

'Cioppino is traditionally made from the catch of the day, which in San Francisco is typically a combination of Dungeness crab, clams, shrimp, scallops, squid, mussels, and fish all sourced from salt-water ocean; in this case the Pacific. The seafood is then combined with fresh tomatoes in a wine sauce. . .

Cioppino was developed in the late 1800s primarily by Italian immigrants who settled in the North Beach neighborhood of San Francisco, many from the port city of Genoa. When a fisherman came back empty handed, they would walk around with a pot to the other fishermen asking them to chip in whatever they could. What ever ended up in the pot became their Cioppino. The fishermen that chipped in expected the same treatment if they came back empty handed in the future.[2][3] It later became a staple as Italian restaurants proliferated in San Francisco.'

https://en.wikipedia.org/wiki/Cioppino

It sounds like whoever wrote the recipe secifying sea bass was suffering badly from restaurantitis. Chilean sea bass has been a foodie fad over the last 20 years and the endangered because of it. That's why it's so expensive. There are other fish in the sea, at least temporarily, and some of them have been sustainably fished.

but have never made it. Have made/attempted bouillabaisse, tho.

have firm flesh that will hold together in soup. No to delicate fish that will break apart too easily, unless price and flavor come together to make adding something very gently toward the end a good choice also.