Iranian Journal of Ichthyology
Volume:2 Issue: 2, Jun 2015

The systematics, morphology, distribution, biology, economic importance and conservation of the milkfish (Chanos chanos) of Iran are described, the species is illustrated, and a bibliography on this fish in Iran is provided. It is characterised by a compressed and oblong body, small, toothless and terminal mouth, non-protractile upper jaw, lateral pouches on the posterior part of the branchial chamber forming an epibranchial organ and presence of intermuscular bones. The milkfish resembles members of the family Clupeidae (herrings) but is distinguished by a low number of branchiostegal rays (4 as opposed to 6-7), the presence of a lateral line, and the absence of scutes along the belly. Chanos chanos is found from the African coast, Red Sea and Persian Gulf to the southern Pacific coast of the U.S.A. and to Peru, and north to Japan and south to Australia. Usually found in littoral waters of the ocean, rarely entering rivers but often found in estuaries. The milkfish has been acclimatised to freshwater ponds.

Distribution of the genus Chondrostoma in Iran, which is mostly known from the Caspian Sea, Tigris River, Kor River and Esfahan basins was mapped. The Kura nase, Chondrostoma cyri is reported from Armenia, Georgia and Iran and it is found in the streams and rivers draining to the western coast of the Caspian Sea from the Kuma River in the north southward to the Kura and Aras River basins in the south. The king or Mesopotamian nase, C. regium is widely distributed in Turkey, Iran, Iraq and Syria. It is found in the Qweik and Orontes River basins (Mediterranean Sea basin), the endorheic Esfahan basin and exorheic Tigris-Euphrates and Zohreh River basins (Persian Gulf basin). The Kor nase, C. orientale is distributed only in the endorheic Kor River basin of Iran and prefers medium to large streams and also large rivers.

The bottom trawl selectivity parameters (22mm cod-end mesh size) were determined for Saurida undosquamis, Mullus barbatus, Upeneus pori, and Pagellus erythrinus along Karatas coasts of Turkey in northeastern Mediterranean waters during fishing season for the year 2002-2003. The lengths at first capture (L50) values for S. undosquamis, M. barbatus, U. pori and P. erythrinus were 12.57, 9.27, 10.20 and 7.20cm, respectively. When lengths at first maturity of these species were taken into consideration, it was concluded that bottom trawl fisheries carried out in breeding areas creates a high fishing pressure (overfishing) on all species and enlarging the mesh size of the net is not enough to prevent the high fishing pressure on these species.

The ontogeny of the gill structure in starlet (Acipenser ruthenus) was studied histologically from hatching up to 50 days post hatching (dph). Based on the obtained results, the first developmental phase of the biological systems in this species was started from hatching with an intense organogenesis and the second phase from 9 dph with the beginning of exogenous feeding. The gill anlage was visible in the pharyngeal region at 1 dph. The mouth and gill slits opened at 2 dph along with the formation of four pairs of the primordial gill arches. At 3 dph, the primordial gill filaments formed. The development of the primordial lamellae and pseudobranch were observed at 8 dph. The primordial gill filaments of the pseudobranch were appeared at 9 dph. The chloride cells appeared at 8 dph on the base of the gill filaments. The gill structure of the sterlet larvae at 31 dph was similar to that of the adults. The results of this study provided a proper indicator for aquaculture practice of starlet.

This study was carried out to determine the appropriate size of Caspian trout (Salmo caspius Kessler, 1877) juveniles for releasing into the rivers that enter south of the Caspian Sea for stock enhancement, or possibility of cage culture in the Caspian Sea. A total of 1611 specimens in 4 weight groups of 5, 10, 15 and 20g were exposed to 3 salinity trials which include Caspian Sea water (11- 11.5ppt), water of 7ppt salinity and freshwater (as control). Each trial was done in 3 replicates. The blood samples and tissue fixations were taken from juveniles of control group (in freshwater) and 3, 6, 12, 24, 72, 168 and 240 hrs after exposure of fish in different salinities to determine the dynamics of some parameters that can give characteristic of osmoregulatory process and morphological changes of organs that take part in osmoregulation. The results of osmolality and ions measuring concurrently showed that all weight groups can live in salinity of 7ppt and they maintain the osmolality and ion concentrations. In the Caspian Sea water, weight groups excluding 5g juveniles showed the same result. The number and size of gill chloride cells were not changed significantly (P>0.05) after 7 days of fish exposure in the Caspian Sea water and in water of 7ppt salinity for 5g juveniles, whereas within weight groups of 10, 15 and 20g in Caspian Sea water and groups of 15 and 20g in water of 7ppt salinity, the increase of chloride cells were observed (P

The present study was conducted to provide a detailed descriptive osteology of Barbus cyri from Southern Caspian Sea for the first time and comparing it with those of B. lacerta from the Tigris and Urmia lake basins. For this purpose, twelve specimens of B. cyri were collected from Safidrud River using electrofishing device and fixed in 10% buffered formalin. Then, the specimens were cleared and stained with alcian blue and alizarin red for osteological examination. A detailed description of the osteological features of B. cyri was provided. Based on the results, several differences were observed between the two species. Barbus cyri can be distinguished from B. lacerta by having three pharyngobranchial, a consumptive neural spine of second centrum and having 3rd and 4th vertebra with posterior position of neural spines.

This study presents, a comprehensive dataset that documents and provides a new and updated checklist of the freshwater fishes of the poorly known area of Iran including Makran and Mashkid River basins in the east and south eastern Iran. The list is based on historical literature records and taxon occurrence data obtained as a result of extensive field expeditions, examination of ichthyological collections and literature review. The total confirmed and recently not confirmed freshwater fish species of the Makran and Mashkid basins comprise 28 species in 21 genera, 9 families, 6 orders and one class. The most diverse order is the Cypriniformes with 17 species (60.71%) followed by Gobiiformes with 4 species (14.28%), Cyprinodontiformes (3 species, 10.71%), Perciformes (2 species, 7.14%) and Gonorynchiformes and Mugiliformes each with 1 species (each, 3.57%). New species are supposed to be discovered, the taxonomic status of some species has been changed, some are being resurrected from synonymy, and some taxonomic problems remain and are commented on briefly. Eight endemic species (28.57%) in 4 genera and 4 families; and 5 exotic species (17.85%) in 5 genera and 2 families are listed here. The fish taxa were classified into different major groups based on the fish ichthyogeographical origin, ecoregion and ecological factors (tolerance to salt water and mode of life). The depauperate fauna of these basins is a consequence of lacking the diverse habitat and having semi-desert to desert environment (despite marine connection for Makran basin).