Demersal fish live on or near the bottom of the sea or lakes. They occupy the sea floors and lake beds, which usually consist of mud, sand, gravel or rocks. In coastal waters they are found on or near the continental shelf, and in deep waters they are found on or near the continental slope or along the continental rise. They are not generally found in the deepest waters, such as abyssal depths or on the abyssal plain, but they can be found around seamounts and islands. The word demersal comes from the Latin demergere, which means to sink.
Demersal fish are bottom feeders. They can be contrasted with pelagic fish which live and feed away from the bottom in the open water column. Demersal fish contain little oil (one to four percent), whereas pelagic fish fillets can contain up to 30 percent.
Demersal fish can be divided into two main types: benthic fish which rest on the sea floor, and benthopelagic fish which float in the water column just above the sea floor.
Most demersal fish of commercial or recreational interest are coastal, confined to the upper 200 metres. Commercially important demersal food fish species include flatfish, such as flounder, sole, turbot, plaice, and halibut. Also important are cod, hake, redfish, haddock, bass, congers, sharks, rays and chimaeras.
You can find authentic Thai Demersal Fish on many Thai Restaurants in Los Angeles.