جستجوی مقالات مرتبط با کلیدواژه « ماهی سیاه کولی » در نشریات گروه « شیلات »

In this study, mouth morphological development and the importance of size of pellet food at the onset of exogenous feeding, with respect to mouth size from hatching through 60s day after hatching (DAH), were studied in larval and juvenile Vimba bream (Vimba vimba). The samples were randomly taken at 1-8 DAH, then with 2, 5, and 10 days intervals until 60 DAH (being released into the sea). Morphological examinations of mouth were followed using SEM. The length of upper and lower jaws as well as the size of mouth gap at 45° and 90° were calculated to estimate the size of pellet food. The larval mouth opened at 1 DAH and filiform papillae, and lips began to form at 2 DAH. The first taste buds developed at 3 DAH. The larval mouth developed a crescent shape at 4 DAH and the structure of papilla became clear. A number of neuromast cells were observed around the mouth at 8 DAH. Finally, it can be concluded that with the onset of exogenous feeding, Vimba vimba larvae is probably able to ingest and digest 110 µm pellet food since 8 DAH. Thus, since 20 DAH until the end of larval rearing period, formulated diets can only be used.

Results show that this species (122 specimens) has the average total length of 171.2 ±31.6 mm, average total weight of 62.9±19.7 g, and average age of 3.49±0.9 year. Average number of scales on the lateral line is 50.83±1.8, soft rays of dorsal fin were 7.96±0.2, and anal fin rays were 17.58±1.0.The average head length was 24.47±1.9%, eye diameter was 6.1±0.4%, the maximum body height was 26.17±1.4%, height and length of dorsal fin were 20.22±1.5 and 10.96±0.8% respectively, height and length of anal fin were 12.66±0.8% and 18.17±1.5% respectively. The distance between the pectoral and ventral fins was 24.18±1.7% and the distance between the ventral and anal fins was 20±1.5%. The pre-dorsal length was 52.21±1.7% of the standard length.The brood stocks and fingerlings were different in one meristic characteristic and 9 morphometric parameters. Female and male Brood stocks were different in 12 morphometric characteristics, especially in body height, dorsal and anal fin lengths. Also from the appearance of fish point of view the matured males had epithelial turbecles on the head and body, the body color is relatively darker than females. Also the color of ventral and anal fins was more light-red than females.

During years 1999-2001. a series of sampling was carried out in Sefidrud river to study morphometric and meristic characteristics of Caspian Vimba. 149 specimen were collected and then necessary measurments were considered and following results were obtained:T.L= 171.2±31.6mm, W= 62.9±19.7g, age= 3.49±0.9 year, average number of scales on lateral line = 50.83±1.8, branched ray of dorsal and anal fins = 7.96±0.2 and 17.58±1.0 respectively.
The mean morphometric measurments with respect to body standard length (%) were: head length 24.47±1.9, eye diameter 6.10±1.07, body maximum depth 26.17±1.4, dorsal fin heigth and length 20.22±1.5 and 10.96±0.8, anal fin heigth and length 12.66±0.8 and 18.17±1.5, pectoral fin length 18.17±1.2, ventral fin length 14.97±1.1, pecto-ventral fins distance 24.18±l.7 and ventral-anal distance 20.00±1.5 and pre-dorsal distance 52.21±1.7.
Adults and juvenils showed difference in 2 meristic and 15 morphometric parameters. On the other hand, the adult males and females showed difference in 16 morphometric parameters (esp. body depth, lengths of dorsal, pectoral, pelvic and anal fins). Also, adult males have a series of fine epithelial turbecles on head and body and their color is darker with more reddish anal and ventral fins.