Quick Weeknight Fish Stew with Olives

Mussels are often hard to find here, but I lucked up and found a pound of precooked frozen ones at our local market for a very reasonable price. I added them in at the end just long enough to warm them up. I used tilapia for the fish. I couldn't find oil brined black olives, so I'd planned to sub some kalamata olives I had at home only to find they were spoiled, so I omitted them. We all enjoyed this one on a rainy Sat. night with toasted garlic bread for dipping.