Curious to know if the chicken could be substituted with prawns or what other type of fish would you recommend as good substitute?

Here in America, the typical fish selection is so limited and conservative that you can probably sub in almost any inexpensive white-fleshed fish.

Depending on where you live, this might be cod, catfish, halibut, tilapia, snapper, grouper, and a few others.

In addition to prawns, scallops would be a reasonable substitution.

Good luck.

I think prawns would be fantastic! You could use a firm white fish as well, maybe cod or haddock.