Control Of Fish Leeches By Bruno Broughton Control Of Fish Leeches Guidance notes prepared by Dr Bruno Broughton B.Sc. F.I.F.M., Fisheries Management Consultant General Information Fish leeches are often seen on fish during the winter months, and they cause concern for anglers and fishery managers alike.
Leeches feed by piercing the skin of fish and sucking blood through their specialised mouthparts.
Once they are satiated, the parasites can drop off and live on their last meal for a periods of several weeks. They then 'fish' for another fish host by anchoring themselves by one of their two suckers to stones or vegetation, moving the free end around in search of a passing fish. Leeches eggs are small, brown or black, flattened pods which are laid on vegetation, stones or wood debris, often at the water's edge. After hatching, the young leeches must find a fish host within a couple of weeks. Leeches can cause direct wounds to fish and leave sites for secondary infections.