I'making cioppino for the first time and the recipe calls for a fennel bulb but the store is all out. Can I sub something???

Fennel seed is what I would turn to as well. Fennel pollen is difficult to find and expensive (although I do love it). Pernod is interesting (I love it as well) but be aware that it is very high in alcohol at 43%.

Thank you for all tour advice!!

Looking for anise flavor maybe a dash of Pernod would work might want to simmer it a bit to get the alcohol out.

You could use celery - similar texture, but different flavor. You could add a small amount of ground fennel seed or fennel pollen to get the flavor.

I wonder if the fenal seeds and bok choy would add texture and taste? Or would the bok choy alter the taste too much?

No great subs come to mind - but I think you would be ok to just leave it out. I'm sure the flavor will be slightly altered, but also sure that it will still be super delicious!

If you have some fennel seeds in your spice cabinet, you might try a tbsp of those...or maybe anise seed.