This leech is an external parasite of cartilagenous fishes such as the marbled electric ray ("Torpedo marmorata"), the common stingray ("Dasyatis pastinaca"), and the thornback ray ("Raja clavata"), and less often of ray-finned fish such as the European plaice ("Pleuronectes platessa"), the black scorpionfish ("Scorpaena porcus") and the red scorpionfish ("Scorpaena scrofa").