Living or occurring in the absence of oxygen.

A median, unpaired, ventral fin located between the anus and caudal fin, usually in the posterior portion of the body. Used to maintain equilibrium and stability.

Anteriormost point at which the anal fin base is attached to the body.

Similar in function but not structure or evolutionary origin i.e. evolved independantly.

To undergo the process of anastomosis.

The connection of separate parts of a branching system to form a network. Sometimes used to describe the process by which a relatively regular, e.g. striped, patterning in juveniles of certain fishes breaks up as they mature.

Member of the copepod crustacean genus Lernaea. Adult females are parasitic on freshwater fishes.

Modified, flexible anal fin rays present in males of some fish species (families Hemirhamphidae and Goodeidae) giving the fin a 'notched' appearance. Not used for insemination like the gonopodium in members of the family Poecillidae but to clasp the female during mating.

A compound bone formed by the fusion of the dermal angular and the cartilaginous articular and comprising the posterior part of the lower jaw.

Member of the phylum Annelida which comprises a large group of segmented, usually elongate, worm-like invertebrates. Contains both earthworms and leeches among others.

A fish species which naturally completes its life cycle within a year at the end of which it dies leaving behind fertile eggs which typically survive in the soil and hatch during the next rainy season. Often used in reference to certain South American and African killifishes.

Absence of oxygen.

Depleted of oxygen..

Located near or towards the head; forward in position.

Used to refer to the margin of a fin from its origin to its apex.

Refers to the position or direction between the front and side of an object.

See antihelmintic.

Caused by humans. Often applied to the environment.

Substance or medication that destroys or expels parasitic worms from the body. Same meaning as anthelmintic.

A small, paired dermal bone lying lateral to the nasal bone in front of the eye.