Pescatarian in Thailand

I'm planning a trip to Thailand and am wondering how I'll manage and enjoy the local foods. Besides weight/healthy eating issues, I don't eat meat or shellfish but do eat fish. I could go vegetarian but would like to taste as much of the local food as possible. Would restaurants understand my complicated request (yes to fish, no to fish sauce)? Any advice from Asian CCers? What do they eat for breakfast in Thailand?

Sorry if this if the wrong forum. Didn't see a pescatarian one!