Labeo Rohita is included in:
Phylum – Chordata,
Sub-phylum – Vertebrata,
Super class – Pisces,
Class – Osteichthyes.
Body is spindle shaped. It is laterally compressed. The dorsal surface is dark gray coloured and belly is white in coulor. It grows upto 80 cm and weighs about 8 kilograms. The body is divisible into head, trunk and tail.
The head ends with a short, swollen snout. The mouth is sub-terminal. A pair of short, thread like, sensory processes on the snout called maxillary barbels. The jaws are without teeth but the pharynx is provided with three rows of teeth. The paired eyes are without eyelids but a transparent membrane covers the cornea. Two nostrils are situated in front of eyes. The nostrils open internally into olfactory sac but not into buccal cavity. The gills are covered by a large lid called operculum. The space between gill slits and operculum is known as branchial cavity or opercular chamber. The opercular chamber communicates with the exterior by a single aperture.
It is the thickest part of the body and compressed laterally. A lateral line lies on their side of trunk and tail. The trunk is covered with demal cycloid scales. The trunk bears paired (pectoral and pelvic fins) and unpaired fins (dorsal, anal and cloudal fins). The fins are supported by bony fin rays. The caudal fin is a homocercal i.e epichordal and hypochordal lobes are equal. The fins push the fish to move forward. There are 3 apertures – nal, urinary and genital apertures in the trunk region.
The tail is supported by special muscles and acts as efficient oar for propelling in water.