I have a bad feeling about this plate

[Fishking03]

I bought this plate from a friend of my brother in law that runs an antique shop. I have 3 kids so I thought the plate with 3 fishes that may bring good luck. There appears to be a black dot on the plate (looks like a burnt mark). No marks on the plate in the back. The more I read on discussion forum here the more I begin to think this plate is a modern production. Can somebody help me?

[peterp]

20th century, probably.

[Fishking03]

How can you tell that this is a modern piece?