Diagnostic Characters of Carp Fry

Catla

• No. of undivided dorsal fin rays 11, large head, dorsal profile convex and ventral profile concave. No distinct spot on the caudal fin or at the caudal peduncle.
• Margin of the dorsal and caudal fins darker. First ray of the dorsal fin black. Opercular region brightly reddish. No barbells. Lips thick but not fringed.

Rohu

• No. of undivided dorsal fin rays 11, a dark refused transverse band present at the caudal peduncle.
• A pair of whitish or light greyish maxillary barbells present. Lips fringed.

Mrigal

• No. of undivided dorsal fin rays 11, small head and slender body.
• A more or less triangular dark spot at the caudal peduncle. No barbells visible. Lips are thin, not fringed. Tip of the lower lobe of caudal fin has a reddish tinge in large size fry.
• Fry of cirrhinus mrigal can be distinguished by the shape of the caudal spot; where as the posterior edge of the caudal spot is slightly concave.
• In larger fry the lower lip of caudal fin of the former has a reddish tinge while the latter has a whitish tip.

Diagnostic Characters of Advanced Fry and Early Fingerling of Carps

Catla

• Large head, no distinct spot in the body or at the caudal peduncle.
• Dorsal, caudal and anal fins are dark greyish in colour. No barbells. Lips thick, but not fringed.

Rohu

• Dark band at the caudal peduncle persists. Reddish tinge present in the dorsal, pelvic, and anal and caudal fin.
• Both the lobes of the caudal fin have reddish tinge with dirty grey colour along the margins. Lips fringed. Maxillary barbells are prominent. A pair of small rostral barbells is also appearing.

Mrigal

• The spot on the caudal peduncle becomes diamond shaped.
• Barbells are faintly visible. Lips are not continuous. A few longitudinal lines are visible on the body due to the pigments on the scales. This is more conspicuous in preserved specimens.
• The tips of the lower lobe of the caudal fin are vermilion red in colour.

 Identification characters of the important cultivable carps 

Catla

• Head is large with upturned mouth
• No barbells, no jaw teeth but 3 pairs of pharyngeal teeth.
• 3–4 spines and 17-21 fin rays in the dorsal.

Rohu:

• Elongated body,
• Inferior mouth, fringed and thick lipped lower jaw
•  2 barbells, 12–15 rays in dorsal fin.

Mrigal

• Body elongated
• Mouth inferior with thin non-fringed lipped lower jaw.
• 2 barbells, 3 spines and 12–13 rays in dorsal fin.

Silver carp

• Elongated and some what laterally compressed body
• Scales are small in size.

Grass carp

• Mouth terminal with thin lips
• No barbells, tip of the dorsal fin and anal fins are round
• 3 spines and 6–3 rays in dorsal fin
• Scales with greenish shade.

Common carp

• Large mouth protruding forward and possess 2 pairs of barbells, 3 spine and 17–21 rays in dorsal fin.
• Scale carps contain scales throughout the body whereas in mirror carp, only few scales of large size are present.  But in leather carp no scales at all.