THE CYPRINID FISHES (CYPRINIDAE) OF UKRAINIAN WATER BODIES - V. V. Zamorov - 2015

THE GENUS SQUALIUS - SQUALIUS BONAPARTE

Mouth terminal. Anal fin rounded. Lateral line typically with 35-47 scales. About 12 species are known in Europe, Central and Asia Minor, and the Middle East. A single species occurs in Ukraine.

Chub - Squalius cephalus (Linnaeus)

Morphological features: D (II) III (7) 8; A (II) III (7) 8-9; Р I (12, 13) 14-17(18); V I 8(9); l. l. (39) 40-47(48-50); Squ₁ (6,5) 7-7,5 (8), Squ₂ 3-3,5 (4); vert. (38-40) 41-45 (46); sp. br. (6-7) 8-11 (14); d. f. 2.5-5.2 (98,5%), 2.5-4.2 (1,0%), 2.5-4.1 (0,5%).

Maximum length 80 cm, body weight up to 4 kg, lifespan 11-12 years (Fig. 54).

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Fig. 54. Chub Squalius cephalus

The lateral line typically contains (39) 40-47 (48-50) scales. Mouth large. Large-sized fish. Widespread in Europe, Asia Minor, and Transcaucasia. About ten subspecies are known. A single one occurs in Ukraine.

Body elongated, slightly laterally compressed, and rather thick. In adults, the maximum body depth averages 23.8-27.0% (21.5-31.5) of the standard length; as a rule, in fish from lowland rivers, it is significantly greater than the HEAD length, whereas in fish from mountain rivers, it equals or is less than the latter. Dorsal profile gently convex, almost straight. Ventral profile with a faintly defined convexity. Back and belly rounded, hardly laterally compressed. Caudal peduncle short, averaging 21.1-21.9% (19.5-23.8) of the body length. Dorsal fin truncated squarely, slightly rounded at the tip; anal fin always rounded; paired and caudal fins slightly pointed at the ends, the latter with a noticeable notch, its lobes normally equal.

The dorsal fin originates above the middle of the pelvic fin base, sometimes slightly further back; the anal fin is located noticeably behind the vertical line of the dorsal fin origin. Pectoral fins relatively long, averaging more than half the pectoroventral distance. An elongated scale is present on the outer side of the pelvic fin base. Scales large, densely covering the body. Lateral line always complete, curving in a gentle arc toward the belly or running in an almost straight line just below the longitudinal body axis; anteriorly, it extends from the trunk onto the head, where it forms several rows. Head of medium size. Snout makes up almost a third of the head length or slightly more, broad and relatively blunt. Mouth large, terminal, obliquely cut, its tip usually positioned at the level of the middle of the eye. Eyes small, horizontal diameter more than twice less than the interorbital width. Forehead wide, flat or slightly convex, accounting for 34.9-46.3% of the head length. Upper jaw almost reaches the vertical of the anterior margin of the eye; Articulation of the lower jaw with the cranium lies at the level of the vertical eye diameter. Gill rakers short, rather thick, sparsely set. Pharyngeal Teeth strong, arranged in two rows, usually somewhat folded, with a small hook at the tip. Abdominal cavity dark or reddish-brown.

In Ukraine, it occurs in the basins of virtually all major rivers, in large lakes and reservoirs, occasionally recorded in limans, and was previously noted in the Dnieper-Bug Liman.