Anal redness in European eels as an indicator of infection by the swimbladder nematode, Anguillicola crassus

Anal redness in European eels Anguilla anguilla is related to the prevalence and mean abundance of the swimbladder nematode Anguillicola crassus and may provide a simple. non-invasive diagnostic tool for A. crassus infection. (C) 2003 The Fisheries Society of the British Isles.