(Chiefly of fish) living close to the floor of the sea or a lake:demersal fish...
The starkest fact highlighting the plight of fishing is that the amount of adult demersal fish - those living on the seabed - has fallen by 90 per cent since the early 1970s.
A small beginning has been made to developing the theory of metapopulations of demersal fishes, frequently in the context of reef fish management.
These fish have demersal eggs, but do not bury the eggs and do not attach them to specific substrates.
Often contrasted with pelagic.
Origin
Late 19th century: from Latin demersus (past participle of demergere 'submerge, sink', from de- 'down' + mergere 'plunge') + -al.