* You might be thinking of a different term: There are various methods for raising fish in enclosed environments, such as:
* Fish pens: These are large, floating enclosures used in open waters.
* Fish cages: Similar to fish pens, but usually smaller and often made of netting.
* Fish ponds: Shallow, enclosed bodies of water, often on land.
* Raceways: Long, narrow channels of water used for intensive fish farming.
* It's a local or regional term: The term "fish pen method" could be used in a specific area or community to describe a particular fish farming technique.
If you could provide more context or details about what you're looking for, I might be able to help you understand the term better.