Demersal fish live and feed on or near the bottom of
seas or
lakes (the
demersal zone). 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 fillets contain little
fish oil (one to four percent), whereas pelagic fish can contain up to 30 percent.