The Associação Portuguesa de Killifilia (Portuguese Killifish Association) is a nonprofit organization based in Portugal, that aims to promote the study, preservation and maintenance of egg laying fishes belonging to the Cyprinodontiformes order, commonly known as Killifish.

The APK was founded on October 24, 1998 and formally constituted on November 16, 1999. It has members from various countries of the world. Membership is open to any single person or organization, from any nationality, that declares to accept the association's Statutes, Rules of Procedure and Code of Conduct.

Of the various activities promoted by APK one can highlight regular member meetings in Lisbon and Porto (organized by regional groups), publication of a bimonthly Journal for free distribution to members, management of a cooperative, maintenance of a Website, participation in national and international killifish and aquaristic events and the organization of an annual international convention. The APK also coordinates the activity of a web based "mailing list" (named "Killifilia") and manages its own public web Forum.

APK maintains protocols and cooperation agreements with various national  (Vasco da Gama Aquarium, the oldest public aquarium in Lisbon) and international authorities (killifish associations of various countries, Société Française d'Ichtyologie and Dr. Jean Huber).