International Journal of Aquatic Biology
Volume:8 Issue: 1, Feb 2020

Objective of the current study was to investigate morphohistology of digestive tract of Iranocichla hormuzensis, one of two native cichlid fishes in Iran. The species present omnivorous feeding habits and restricted in shallow, high temperatures and high salinity water in the Mehran River and its drainages. This species has a terminal mouth with several rows of serrated incisive teeth, which covered the upper and lower lips. Esophagus is a short tubular between pharynx and stomach, stomach is relatively small and sac-shape, and intestine is long. Gastric wall, through the digestive tube, consists of four layers of mucosa, submucosa, muscularis, and serosa with some characters specialized for each organ, such as a well-developed mucosa layer and numerous goblet cell in the ventral section of stomach. Morphohistology of digestive tract of I. hormuzensis supports its generalist diet.

The objective of this study was to identify the anoxygenic phototrophic bacteria in the anaerobic lagoons and facultative stabilization pond of the Vale do Ribeira, Cajati, São Paulo, Brazil, and their correlation with physical and chemical parameters of the ponds’ water. The samples were collected seasonally (spring, summer, autumn and winter) in the sub-surface, intermediate layer and sediment-water interface. We used the PCR/DGGE with pufM 557FGC and pufM 750R primers specific to the reaction center of the photosynthetic phototrophic bacteria for their identification. The amplification products were separated by electrophoresis on denaturing gradient gel. From the bands cut out and sequenced from DGGE, the identified bacteria were Rhodopseudomonas palustris (99% similarity), Chromatium sp. (92%), Thiocapsa sp. (90%), Rhodospirillum sp. (95%), Roseobacter sp. (93%) and other uncultured bacteria.

Limnological survey (October 2013–September 2015) of Maghuri, Khamti Guali and No.11 floodplain lakes (beels) of the Dibru-Saikhowa Biosphere Reserve (DSBR), upper Assam, northeast India (NEI) revealed 210 (184±4) species of zooplankton, belonging 78 genera and 32 families, with several species of global and regional distribution interest. The biodiverse zooplankton assemblage and interesting taxa are hypothesized to habitat diversity and environmental heterogeneity of these wetlands located in the Assam-gateway’- an important biogeographic corridor of India. The monthly richness and community similarities depicted heterogeneity of zooplankton composition of the individual beels. Low abundance is attributed to soft–moderately hard waters with low ionic concentrations. Zooplankton richness and abundance followed no definite pattern of monthly or annual variations; Rotifera > Cladocera influenced overall diversity in the three beels. High species diversity affirmed habitat heterogeneity, while high evenness and low dominance without quantitative importance of any species affirmed ‘generalist nature’ of zooplankton of the different beels. Our results indicated limited influence of individual abiotic factors but CCA registered moderately high cumulative importance of seventeen abiotic factors on zooplankton assemblages of DSBR beels.

Lactic acid bacteria (LAB) are used in the aquaculture industry to improve growth indices and nutrition efficiency of farmed fish. Kefir is a natural probiotic that largely consists of these microorganisms. This study aimed to isolate LAB strains from kefir grains and investigate their effects on the intestinal microbiota and growth indices of juvenile rainbow trout. Based on the results, one isolate was identified as Lactobacillus faraginis (LF) and other one as Enterococcus durans (ED), both were gram positive, non-hemolytic, catalase and oxidase negative. Both strains showed resistance to acidic environments and gastric juice and were able to grow against bile salts i.e. the hydrophobicity potential of both strains was evaluated above 50%. The results showed that both strains had appropriate and acceptable probiotic properties. A total of 480 juvenile fish with were randomly divided into eight groups viz. Control (basal diet), LF1 and LF2 receiving diets supplemented with L. faraginis at 107 and 108 cfu/g, respectively, ED1 and ED2 diets supplemented with E. durans at 107 and 108 cfu/g, respectively, Bactocell group receiving a diet supplemented with commercial probiotic Bactocell PA-10 (1010 cfu/g), combined treatments LF1+ED1 (5×106 cfu/g) and LF2+ED2 (5×107 cfu/g). The strains were prepared in the form of lyophilized powder and added to the basal diet as supplements. Sampling was performed after 0, 30, 15, and 45 days feeding with the diets. In the in vivo investigation, the highest LAB colony counts were obtained for the ED2, Bactocell, LF2+ED2 and LF2 groups, respectively. The highest BWI, SGR, DWG, PER, and CF, and the lowest FCR were observed in the LF2+ED2, Bactocell, ED2, and LF2 groups, respectively. On the other hand, the LF2+ED2, Bactocell and LF2 treatments also had the highest survival rate. Apparently, the use of the tested LAB strains as probiotic in high doses (LF2, ED2) and in combination (LF2+ED2) could improve growth indices, the intestinal LAB population and survival rate in juvenile rainbow trout.

Miscellany in histochemical peculiarity of the olfactory mucosa was studied for localization of axons, mucopolysaccharides, glycogen, protein and lipid in schilbid catfish, Eutropiichthys vacha (Hamilton, 1822). Silver deposition was detected in the abundance of receptor cells in the olfactosensory epithelium and well as marked in the knob and dendrite process of primary receptor cells. The mucous cells with various stages of maturity containing different degrees of mucopolysaccharides were identified by employing the Periodic Acid Schiff's (PAS) reaction in combination with Alcian Blue (AB) test. This combined test imparted purple colour due to PAS for neutral mucin and blue colour for AB reaction due to the presence of acid mucin exclusively. The results of Best’s carmine test indicated considerable amount of glycogen present in the receptor cells, basal cells and supporting cells in the olfactory mucosa. Basic protein and bound lipid were ascertained in the various cells of the epithelial lining and in blood cells of the central core were discussed with behavioural activities of the fish interested.

The Caspian Kutum, Rutilus frisii, is one of the endemic and most important commercial cyprinid species in the southern Caspian Sea. A detailed study on growth and mortality parameters of this species was conducted based on 700 samples collected from commercial catches of beach seining in Guilan and Mazanderan provinces during fishing season 2017-2018. Females were dominated in both studied populations. Size frequency distributions showed significant variation among same sexes and between different sexes. The different WLRs were observed, positive allometric in Mazanderan, and negative allometric in Guilan. There were significant differences in growth parameters between sexes, females were of much greater asymptotic length than males, while the male fish had a higher growth rate and attained a smaller theoretical L∞ size than females. The theoretical maximum length (L∞) was larger than the maximum one recorded during sampling. Based on the Bhattacharya method, the Caspian kutum from Guilan fishing grounds was more diverse, and included nine cohorts, while the population from Mazanderan Province showed only six cohorts. The linearized catch curve based on age composition data showed that total mortality rates (Z) are 1.32 year-1 and 0.63 year-1 for males and females of Guilan, respectively, that of males in Mazanderan is 1.04 year-1 and of females 0.86 year-1. The natural mortality rates (M) were 0.48 year-1 for males and 0.26 year-1 females in Guilan, and was found to be as 0.26 year-1 and 0.45 year-1 for males and females of Caspian kutum caught in Mazanderan. The exploitation ratio (E) was found to be higher than 0.5 for both sexes from Guilan, and to be lower than the expected optimum level of exploitation in Caspian kutum males and females caught in Mazanderan.

This study was aimed to reveal the possible cryptic diversity of the Aphanius vladykovi populations in the Chaharmahal va Bakhtiari Province, Iran using mitochondrial cytochrome-c oxidase subunit I (COI). A total of 30 specimens from the Beheshtabad River, Choghakhor and Gandoman Wetlands, and Brovi, Shalamzar, and Balagholi springs from the Chaharmahal va Bakhtiari Province were collected. The maximum within-population genetic distance based on K2P was 0.28% and this distance was 0.22% between populations of Gandoman and Brovi with Shalmazar, whereas the least genetic distance was observed between Choghakhor and Beheshtabad (0.09%). A total of six haplotypes were observed between the studied specimens. Maximum Likelihood (ML) and Neighbor-Joining (NJ) trees reconstructed and all haplotypes from A. vladykovi specimens collected from non-type localities nested in one group with A. vladykovi from Choghakhor wetland i.e. type locality. The results of this study detected no cryptic diversity in A. vladykovi inhabiting different habitats in the studied region. Hence, it is proposed to consider all the studied populations in conservation measures related to A. vladycovi.

The present study was carried out to enumerate induced breeding technique and larval development of Macrognathus pancalus (Hamilton, 1822) reared under captivity. Five different doses of Ovasis hormone (T1, T2, T3, T4, and T5) with 3 replicas each were administered to the matured brooders to standardize the breeding performance of the target species. The results indicated variation in fertilization rate, latency period, egg output and hatching rate in response to different treatments. Spawning was occurred between 20-24 hrs of injection in all the experiments at 26.33±0.88°C water temperature. Among all the experimental trials, the highest fertilization rate was observed in T3 (96.15±0.60) of E2 and the highest hatching rate was observed in T3 (92.49±1.00) of E2. The present work elucidated the viability of seed production of M. pancalus reared under confined condition which will useful for aquaculture and conservation.