After de Selys Longchamps (1842), the otter in Belgium was a widespread species along all the full of fish rivers and was regarded as a pest namely in the fishponds of the Campine. This animal becomes extremely rare now: in Wallony, we only recorded one place where cubs are reared every year. The main reasons for this steep population decrease are well known: i. the otter has been systematically destroyed by hunters, fishermen and trappers who were receiving bounties till 1965 ! ii. the water pollution and the radical changes of the rivers physical characteristics (dredging, straightening and reshaping the river beds or banks) have had disastrous effects on fish, the main food resource of the otter. iii. a lot of previous suitable habitats have been destroyed due to for example draining of swamps and marshes and concreting the river banks. A comprehensive study of the fish populations in Wallony reveals that a small number of streams are still inhabited by relatively undamaged fish communities. Most freshwaters are polluted at different levels, some in a chronic way, others irregularly and many of them have been damaged by hydraulic works so becoming unsuitable for the otters because of a drastic reduction of their fish biomass. In such circumstances it seems likely that we cannot be really optimistic as far as the otter's future in our country is concerned. The last places where otters can still be found today must be inconditionnally protected against every disturbance of whatever type; but those measures will only help if a strong program is undertaken without delay intending to improve the water quality. An educational campaign is also urgently needed.