Lepeophtheirus pectoralis is a species of parasitic copepod from the northeast Atlantic Ocean, and the type species of the genus Lepeophtheirus.

[1] It is a parasite of flatfish, with the European flounder (Platichthys flesus), the plaice (Pleuronectes platessa), and the dab (Limanda limanda) as the most frequent hosts.

[2] It feeds on the mucus, skin, and blood of the fish, with egg-producing females infecting the pectoral and pelvic fins of the host, while immature individuals and males are found on the rest of the body.

[3] Its lifecycle consists of five phases and 10 stages.

[4] Multiple generations are apparently produced per year, which show differences in longevity, size, and fecundity.