Philometridae is a family of nematodes belonging to the order Rhabditida.
[1] All Philometridae are obligate tissue parasites of fish.
[2] First-stage larvae are ejected into the water, and develop to the third stage if they're eaten by a cyclopoid.
Once the copepod is eaten by a fish, the larvae develop into adults and mate.
Pregnant females migrate to a final site just under the fish's skin, in the swim bladder, or in the coelom; males die soon after mating and in many Philometridae species they have never been described.