Fish dish for wedding reception

Our son is getting married at the end of May. He does not eat meat, which goes for many of his friends, as well.

To add to this dilemma, the venue does not have cooking facilities. The caterer will be cooking everything on a big cooker.

We are thinking about enough fish for 100 maybe less, people.

Any ideas or suggestions? We will be able to keep everything warm.

My husband is allergic to shellfish, so we want to steer clear of that....

Many thanks...