I've never seen this done in Mexico but I bet there's a village somewhere that steams fish in hoja santa/acuyo leaves. I've done something similar where I steamed fish in a corn tamal wrapper but I had a delicate sole on hand. I also wanted something quick-ish and easy.
I marinated the fish in olive oil, garlic, a small splash of pineapple vinegar, salt, thinly-sliced zucchini, onions, and Oregano Indio. The fish was later wrapped into sloppy packets and tied with butcher twine and steamed for about 10 or 12 minutes. The zucchini really needs to be thin so I used a mandolin.
I bet you could do the same with grape or fig leaves. If the fish were sturdier, you might grill them as well.