Taxonomy of Finfish

2.1.5.8 Eyes

Eyes mainly used for seeing food, enemies and predators are placed in most fishes dorso- laterally (at the sides) along a mid-axis line of the body. However this position may vary depending upon the habitat of the fish. It may be superior or inferior. Many gobioid fishes have the eyes placed on the top of the" head. Species of Oxyurichthys. Bathygobius. Boleophthalmus have the eyes placed on top ofthe head. Mugil corsula has protruding eyes on the top (Fig. 19 A). In such cases the distance between the eyes becomes short. Puffer fishes, gouramies also have such an arrangement. The eyes in these cases are large. In some catfishes the eyes are placed low so that they are visible from below the ventral surface. Chandramara chandramara (Fig. 19 B), Horabagrus brachysoma, Ompok and Ailia species show this kind of placement. The catfishes browse at the bottom and hence the eyes are situated at this level. The eyes are generally large in size or moderate, but in the eels and hill-stream fishes they are, small; the latter being denizens of fast powing shallow 'streams, with too much light penetrating, larfe eyes would be a disadvantage. In Brachyamblyopui burmanicus (eel like goby) the eyes are minute and hidden (Fig. 19 C) they are minute and hidden. The eyes are subcutaneous and they may be circular, oval in shape. Some cave dwelling fishes are totally blind.

Fig. 19. Eyes. A. Superior Mugil corsula. B. Inferior visible from below ventral surface Chandramara chandramara. C. Minute reduced, hidden Brachyamblyopus burmanicus.