Iranian Journal of Ichthyology
Volume:6 Issue: 1, Mar 2019

The systematics, morphology, distribution, biology and economic importance of the gobionids of Iran are described, the species are illustrated, and a bibliography on these fishes in Iran is provided. There are three native species in the genera Gobio and Romanogobio found in northeastern and northwestern Iran respectively and a widely introduced exotic species Pseudorasbora parva.

The present study describes the sex ratio (SR), distribution of length-frequency (DLF), relationship of length-weight (RLW), relationship of length-length (RLL) and condition factors of Mystus tengara, a small indigenous freshwater fish species. A total of 881 specimens ranging from 4.3-11.4 cm LT (total length) and 3.8-9.6 g WB (body weight) were investigated in the Ganges River of Rajshahi, northwestern Bangladesh from January 2010 to December 2010. The overall sex ratio showed significant differences from the expected value of 1:1 (df=1, χ2=8.9, P<0.001). The significant difference was found in the DLF (LT) between the sexes (Two tailed, P<0.001). Overall, the allometric coefficient b of the RLW was closed to the isometric value (b=3.088), although it suggested negative allometric growth for males (b=2.956) whilst positive allometric growth for females (b=3.198). The results further indicated that the RLL were highly correlated (r2>0.91, distribution of length-frequency). The value of Fulton’s condition factor (KF) was ranged from 0.9 to 1.2 for male and 1.0 to 1.5 for female M. tengara. Also, relative weight (WR) was significantly higher in females (WR>100) than in males (WR<100) indicating imbalance habitat with food availability.

The sharpbelly, Hemiculter leucisculus, an invasive species, has expanded its range throughout much of Asia and into the Middle East. However, little is known of its reproductive information regarding spawning pattern and season that could possibly explain its success as an invasive species. This research is the first presentation of its reproductive characteristics, which was conducted based on 235 individuals collected monthly throughout a year from Sefid River, in the southern Caspian Sea basin. Age, sex ratio, fecundity, oocytes diameter and gonado-somatic index were calculated. Regression analyses were used to find relations among fecundity and fish size, gonad weight (Wg) and age. The mature males and females were longer than 93.0 and 99.7mm in total length, respectively (+1 in age). The average egg diameter ranged from 0.4mm (April) to 1.1mm (August). Spawning took place in August, when the water temperature was 23 to 26°C. Average gonado-somatic index values for females at the beginning of the reproduction period (March) and in ripe mature spawning females (August) were 2.90% and 16.97%, respectively. The averages of absolute and relative fecundities were 19978.6 and 607.1 eggs, respectively. The absolute fecundity was significantly related to body weight, ovary weight and age. A potentially high reproductive capacity, comparatively small eggs, short time of eggs’ development, fast sexual maturation, short life span, tolerance to a wide range of environmental conditions, all promote the invasion of this invasive sharpbelly in freshwater ecosystems of the temperate climate zone.

In Indian freshwater aquaculture, which largely depends on carps, diseases have become a major problem. This study evaluated the health status of Catla catla, Labeo rohita, Cirrhinus mrigala and Labeo bata cultured in West Bengal, India by determining the Health Assessment Index (HAI) and coefficient of variation (CV) of HAI values of each species as well as the superoxide anion production. The annual mean HAI value was the highest for L. rohita (77.51) and least for L. bata (55.30). The highest and lowest CV of HAI values were recorded for L. bata (95.80) and C. mrigala (52.55), respectively. The HAI values correlated negatively (P<0.05) with temperature. The HAI distinguished successfully among the species, seasons and sampling areas on the grounds of temperature and water quality, with higher index values recorded in carps grown in poorly managed ponds. Labeo bata exhibited higher immune responsiveness compared to other carps. Labeo rohita was the most susceptible to diseases. The results on the high production of oxygen radicals by phagocytic cells of L. bata together with low HAI and high CV values suggested that this species may resist biotic and abiotic stressors well under culture conditions. The results suggested that HAI and superoxide anion production can be used to assess the health status of carps under the culture conditions.

Morphological variation among Cyprinion species in Iran was studied using landmark-based geometric morphometrics. A total of 848 specimens were caught from five basins throughout Iran during 2013-2015. A total number of 15 landmark-points were defined and digitized on 2D pictures. Despite of intraspecific differences among Cyprinion fishes, CVA divided all populations into three major groups viz. C. macrostomum, C. kais and C. tenuiradius (group X), C. watsoni and C. microphthalmum (group Y) and C. milesi (group Z). According to the results, C. macrostomum group can be distinguished from other groups by having deeper body, least head length and depth, the longest dorsal-fin base and least caudal peduncle length. Cyprinion milesi has the longest anal-fin base, least body depth, deepest caudal peduncle and longest head. Cyprinion watsoni has the longest caudal peduncle and least dorsal-fin base and C. microphthalmum is distinguished by having the least caudal peduncle length and depth. The main reasons of observed intraspecies morphological diversity among the fishes is proposed to be some phenotypic plasticity related to climatic and zoogeographical factors. The results suggest that the most possible factor influencing morphological variations among Iranian Cyprinion species is habitat related differences.

Gentamicin is known to stimulate the production of reactive oxygen species and lead to renal damage in some groups of vertebrates through oxidative stress. The kidney regeneration of the killifish Aphanius furcatus was studied after gentamicin-induced oxidative stress. In addition, we evaluated the possible role of vitamin C as an antioxidant in the reduction of renal toxicity. A total of 24 specimens (3.5-4cm in total length) were divided into four groups: In group-I two fish specimens treated with 7.5µl of normal saline injection; in group-II, 10 specimens received 10µg/g body weight (b.w) gentamicin; in group-III, two fish were treated with totally 60µg/g b.w vitamin C; and in group-IV, 10 specimens received both 10µg/g gentamicin and 60µg/g b.w vitamin C. The kidney tissues of group-I, III and IV were sampled during the nephrotoxicity phase (i.e., 10 hours post injection (hpi) to 5 days post injection (dpi)) and kidney tissues of group-II sampled daily for 10 dpi until regeneration completed. The kidney regeneration of A. furcatus through nephron neogenesis was detected by newly formed nephron on 8 dpi, and it is completed on 10 dpi. Our histological results in gentamicin-induced oxidative stress (group-II) clearly showed that the most severe damage is occurred in the kidney tissue within 1-4 dpi. However, in the specimens that antioxidant therapy supplied with vitamin C (group-IV), damage effect of gentamicin has remarkably repressed within these days. The outcome of this study revealed that administration of vitamin C is effective in reduction of gentamicin-induced nephrotoxicity in A. furcatus. Vitamin C reduces the toxicity effect of gentamicin by reduction of free radicals and reactive oxygen species (ROS) through its antioxidant activity. Therefore, using vitamin C together with gentamicin enhances the body resistance to the stress condition and reduces the toxicity effect of gentamicin.

In recent decades, climate change and other anthropogenic pressures have seriously influenced freshwater biodiversity to decline faster than terrestrial biodiversity. This trend is likely to be continued in the future. We assessed the impact of climate change on the distribution of brown trout in Iran by simulating their conditions under optimistic and pessimistic climate change scenarios (RCP 2.6 and RCP 8.5) in 2050 and 2080 by using species distribution models (SDMs) tool and ensemble forecasting approach. The results showed a significant reduction in the distribution range of this species (100%) in our database in all optimistic and pessimistic climate change scenarios. Moreover, no new potential sites were predicted in those scenarios. These outcomes seriously warn that a conservation and management plans are required to protect this species in future.