Rod Kochichthys
- Kochichthys flavofasciatus (Kamohara, 1936)
Actinopterygii > Perciformes > Pinguipedidae
Rod Kolpotocheirodon
- Kolpotocheirodon figueiredoi Malabarba, Lima & Weitzman, 2004
- Kolpotocheirodon theloura Malabarba & Weitzman, 2000
Rod Konia
- Konia dikume Trewavas, 1972
- Konia eisentrauti (Trewavas, 1962)
Actinopterygii > Perciformes > Cichlidae
Rod Konosirus
- Konosirus punctatus (Temminck & Schlegel, 1846)
Rod Kopua Hardy, 1984
- Kopua japonica Moore, Hutchins & Okamoto, 2012
- Kopua kuiteri Hutchins, 1991
- Kopua nuimata Hardy, 1984
Pisces → Actinopterygii → Gobiesociformes → Gobiesocidae
Rod Koreocobitis
- Koreocobitis naktongensis Kim, Park & Nalbant, 2000
- Koreocobitis rotundicaudata (Wakiya & Mori, 1929)
Actinopterygii > Cypriniformes > Cobitidae
Rod Kosswigobarbus
- Kosswigobarbus kosswigi (Ladiges, 1960)
Rod Kottelatia Liao, Kullander & Fang, 2009
- Kottelatia brittani (Axelrod, 1976)
Rod Kottelatlimia
- Kottelatlimia hipporhynchos Kottelat & Tan, 2008
- Kottelatlimia katik (Kottelat & Lim, 1992)
- Kottelatlimia pristes (Roberts, 1989)
Actinopterygii > Cypriniformes > Cobitidae
Rod Koumansetta
- Koumansetta hectori (Smith, 1957)
- Koumansetta rainfordi Whitley, 1940
Actinopterygii > Perciformes > Gobiidae