Comparative study of Mesencephalon of two Cypriniformes in relation to feeding Habits

In vertebrates like fish, mesencephalon or mid brain consists of two regions optic tectum (OT), that act as centre for processing visual impulses and generating motor response and tegmentum containing nerve tracts. Both structural and physiological properties of OT helps to know the mechanism of organizing behaviour. Present paper analyses the midbrain (mesencephalon) of two different fishes, Carassius auratus and Botia striata with respect to its feeding behaviour. Both these aquarium fishes belongs to cypriniformes order, but exhibit different feeding behaviours. The OT of Carassius auratus were large with well-developed Optic Tectum, Torus longitudinalis (TL), Tectal commissures, tegmentum, and torus semicircularis (TS). The nuclear areas found are nucleus isthmi (NI) and nuclear interpeduncularis (NI). Five well developed tectal layers are Stratum opticum (SO), stratum griseum fibrosum superficialis (SGFS), Stratum griseum Centrale (SGC), Stratum album Centrale (SAC) and Stratum griseum periventricularis (SGPV) with three sub divisions of SGC. This mid brain structures have critical roles in vision in surface feeding Carassius auratus while in Botia striata the optic lobes possess poorly developed structures. The nucleus isthmi and nucleus interpeduncularis are not developed. In Botia striata tectal layers are also not well developed as in C.auratus indicating less vision use for feeding.