Sociedad Española de Killis, S.E.K.
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External morphology
Killifish have a set of morphological and biological characteristics that distinguish them from other families. The possession of teeth and pharyngeal jaws are lined with small conical teeth that may have several cusps (systematic). The mouth is usually small and protractile. Meg.iprognathus exception would be for example. The top of the head is often flattened, more pronounced in fish that are markedly surface. The upper jaw is formed only by the premaxillary bone, with little mobility, lack of jaw only present in the lower jaw is clearly mobile, as has been said before thrusting, ie can project forward when capturing food.
They are of small size, 20 to 400 mm. and on average between 40 to 60 mm. The body is generally cylindrical in shape although it is sometimes higher than wide, and covered with cycloid scales (which is also a primitive character) almost always large, sometimes showing small spines (Us) with protrusions on the outer edge (ctenoid scales). Dorsal and anal fins are located on the back of the body and the tail has sometimes lyre-shaped or standard (Aphyosemion, Pterolebias), sometimes a couple of extensions filaments (Aphyosemion, Procatopus, Marateca). Ventral or pelvic fins have abdominal position, that is delayed in the body, very near the anus, which is a primitive character. In the more advanced members become pelvic fins thoracic, ie below the head with the pectoral fins. This occurs in the Procatopodinos.
lLack adipose fin, as well as all trace of barbels, or barbels. The lateral line is composed of neuromasts (sensory organs) may be complete, starting, incomplete or absent in body but always present in the head.