FISH OF THE FAMILY CYPRINIDAE IN THE WATER BODIES OF UKRAINE - V. V. Zamorov - 2015

GENUS IDUS - IDUS HECKEL

Mouth terminal. Anal fin emarginate, sometimes truncated. Pharyngeal Teeth typically 3.5-5.3. Two species are distributed in Europe, Siberia, the Amur basin, and China. A single species occurs in Ukraine.

Orfe (Ide) - Leuciscus idus (Linnaeus)

Morphological features: D III (7) 8 (9); A III (8) 9-11; P I (II) (13-14) 15-17 (18); V I - II (7) 8 (9); l. l. (52-54) 55- 60 (61 -62); Squ₁ 8-10 (11); Squ₂ (4) 5-8 (9); vert. (37, 38, 40-41) 42-47 (48); sp. br. (9) 10-13 (14-15); d. f. 3.5-5.3 (>75%), 2.5- 5.3 (>15%), 3.5 - 5.2, 3.4-5.2, 2.5-5.2, 3.4-4.2, 2.4-4.2, 2.4-5.2, 2.4-4.2, and other variations. Maximum length 50 cm, body weight up to 4 kg, lifespan 13-15 years (Fig. 56).

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Fig. 56. Orfe Leuciscus idus

Body moderately elongate, slightly compressed laterally. In adult fish, its greatest depth exceeds one-third (sometimes slightly less) of the body length and is twice the body width.

Dorsal profile slightly convex, nearly straight, with a distinct hump just behind the HEAD. Ventral profile smoothly convex, occasionally completely straight in the middle. The back anterior to the dorsal fin and the belly immediately posterior to the pelvic fins (especially in juveniles) are somewhat laterally compressed. Caudal peduncle short, averaging 19-22% of the body length. Dorsal fin truncated, with a faint notch in young fish, slightly rounded at the tip. Anal fin typically with a well-defined notch. Paired fins rounded, sometimes slightly pointed at the tips (especially the pectorals). Caudal fin distinctly notched, with the upper lobe usually slightly longer than the lower, or both of equal length. Dorsal fin origin located behind the vertical of the posterior margin of the pelvic fin base; anal fin origin situated noticeably behind the vertical of the posterior margin of the dorsal fin base. Pectoral fins fairly long, exceeding half the pectroventral distance.

An elongated scale is present on the outer side at the Base of the pelvic fins. Moderately sized scales densely cover the body.

Lateral line complete, forming a faint arch towards the belly, extending anteriorly from the trunk onto the head, where it runs in several rows. Head relatively small, its length on average usually less than the pectroventral distance. Snout relatively short, blunt, sometimes slightly pointed at the tip. Mouth small, terminal, obliquely set. Its apex lies at the level of the longitudinal eye diameter or slightly lower. Eyes small, noticeably shorter than the snout length in adults. Forehead wide, convex, its width half the head depth at the nape. Upper jaw always shorter than the lower and noticeably failing to reach the anterior margin of the eye. Lower jaw articulation located slightly posterior to the vertical from the anterior margin of the eye or almost directly beneath it. Gill rakers generally short, quite robust, some broadened at the tip, sparsely set. Pharyngeal teeth robust, arranged in two rows, cylindrical, smooth (neither serrated nor folded), hooked at the tip. Abdominal cavity light (yellowish).

Two subspecies are known. Only one subspecies occurs in Ukraine - the ide (orfe) - Leuciscus idus idus (Linnaeus).

Widespread in Central Europe, Siberia, and the Aral Sea basin.

In Ukraine, it inhabits the basins of virtually all rivers, large lakes, and reservoirs, and has occasionally been recorded in estuaries. Absent from Crimea.