I was offered to walk the local market and thought this fishmonger had the right idea. She filleted a large cat fish from the Mekong, rather quickly and swiftly with a long knife. Interestingly most people local believe that the river is fresh water, when in fact it is brackish water, a mix of sea and salt. The salt water concentration is approximately 10/14% and so fish species are mostly adaptable.
The fish monger has a decent technique but lacks the tools and set up. Working in a seated position seems to work for her but the surface area (a small round board) is insufficient.