International Journal of Aquatic Biology
Volume:11 Issue: 3, Jun 2023

Rita rita, a freshwater catfish from the Bagridae family is facing threats of extinction due to over-exploitation and the loss of breeding grounds owing to anthropogenically-driven ecological changes in their native habitat. River Ganga is one of the most important rivers of India, which is affected by industrial and urban waste disposal, unsanitary rituals, and other anthropogenic activities. Therefore, the present study was undertaken to assess the feeding and reproductive biology of R. rita which is native to India and Asian countries. A total of 260 R. rita samples were collected from the Narora site of River Ganga on a monthly basis. Data on feeding habits, feeding intensity, Gonadosomatic index, and maturity stages based on macroscopic and histological studies, fecundity, and sex- ratio were examined. The gut contents of R. rita were composed mainly of molluscs, fishes, insects, crustaceans, annelids, and detritus. RGLs varied significantly with fish size but stayed within the omnivore feeding category. From the month of May to July, females and males had higher GSI values. The fecundity of the sampled R. rita specimens ranged from 9464-72,678 in different size classes. Fecundity was found to be linearly related to body length, body weight, and ovarian weight. The average male-to-female ratio was found to be 1:2.6.

The reproductive biology of ornamental fish species from coral reefs is poorly studied despite increasing demand in the aquarium trade industry. Aspects of the reproductive biology of the Vagabond butterflyfish, Chaetodon vagabundus Linnaeus, 1758, from Iligan Bay, Southern Philippines were investigated from August 2021 to August 2022. Monthly samples of 30 to 45 individuals per class size with a range of 9 to 14.1 cm (TL) were collected to examine the sex ratio, maturity stages and spawning period, gonadosomatic index (GSI), length at first maturity (L50) and the batch fecundity (BF) of the species. The sex ratio showed female dominance (1:1.42) among size classes and across months. The spawning period indicates a peak during the inter-monsoon or warm months (April and May) and extends beginning of the Southwest monsoon period (June and July). These were supported by the relatively higher gonadosomatic index (GSI) recorded during these months. Histological examination showed that the ovaries during this period had the presence of numerous tertiary vitellogenic and hydrated oocytes and post-ovulatory follicles. At the same time for testes, there are occurrences of dense spermatozoa in the lumen of tubules in testes. This served as confirmatory evidence in support of the spawning period. The length at first sexual maturity of males (10.58 cm TL) was slightly shorter than females (10.91 cm TL). Fecundity increased with the fish’s total length and weight showing a non-linear relationship that was best described by a power function. This study highlighted the valuable data produced that are required for the management of the population stock of this species.

Interspecific predator-prey interactions play an important role in the structure of communities. However, predation events in the wild are rare, and difficult to observe, and rarely documented. The objective of this work is to report the attempted predation on Hatcheria macraei by some of the salmonids with which it occurs in syntropy. During a survey of ichthyofauna in the Castaño River, an adult specimen of H. macraei was captured with evidence of a bite on the caudal fin. Despite not having been able to make the specific identification of the predator in the predation attempt on H. macraei, this report adds to the enormous base of information on the devastating effects of introduced salmonids on aquatic ecosystems and the native species that live there inhabit. It is necessary to control the expansion of salmonids, by protecting areas of high value for native fish and prohibiting future aquaculture projects to prevent the invasion of this species to new locations in these aquatic ecosystems.

The current study was conducted to investigate the possibility of using Lactic acid bacteria LAB isolated from the intestines of common carp, Cyprinus carpio, as dietary probiotics to enhance the nutrition and growth of common carp juveniles. The bacteria were cultured on MRS agar and their cultural and biochemical characteristics were confirmed. The isolated probiotic bacteria were used as dietary supplements at concentrations of 106, 107, and 108 and their effect on the nutrition and growth of common carp fingerlings was evaluated. The results showed clear positive effects of adding the probiotic Lactobacilli in fish feed, with a relative growth increase from 105.26 to 178.14% with increasing probiotic concentration compared to the control. The feed conversion ratio also improved from 2.94 to 1.83 with increasing levels of probiotics compared to the control. In addition, all other indicators improved, including weight gain, specific growth rate, protein efficiency ratio, digestibility, and beneficial intestinal flora, with increasing probiotic concentration in the feed compared to the control, with a significant difference. It was concluded that LAB isolated from the intestines of common carp.can be effectively used as probiotics in common carp C. carpio fingerlings feed, with positive results.

To evaluate of water quality of the Zayandeh River using some macrobenthos as biological indicators, five sampling stations were selected upstream of the river. Sampling operations were done monthly for one year in all stations with three replications using a Surber sampler. Identification and counting of invertebrates were done using standard methods under a binocular microscope. To evaluate the water quality, four biological indicators, including Shannon-Wiener, Hilsenhoff, BMWP, and ASPT indexes were applied. Data analysis and calculation of studied indicators were done using Species Diversity and Richness version 4 (SDR4) software. Based on the results, the Zayandeh River water quality was evaluated in the range close to pollution. The Shannon- Wiener index categorized the Zayandeh River in the range of moderate pollution, the Hilsenhoff index assessed most of the stations with severe organic pollution, and the BMWP index classified the stations in the biologically acceptable range. In conclusion, the water quality of the Zayandeh River is classified as biologically acceptable but not stable.

This study investigates the fungal biodiversity of water and sediment samples from some waterbodies and their ability to degrade Methyl orange (M.O.) on a solid medium. Ten fungal genera were isolated, and the genus Aspergillus represented the highest percentage (70%). Sixteen fungal species were isolated that 88% of which (14 species) belonged to anamorphic fungi. Trichoderma sp. showed the highest percentage (40%). Out of the 16 isolated fungi, Aspergillus flavus, A. niger, and A. terreus showed the best result for decolourising M.O. on a solid medium potato dextrose agar. These fungi isolates were selected to test their ability to biodegrade M.O. in a liquid medium supplemented with 50 mg.L-1 M.O. as the sole carbon source. Based on the results, after 7 days of incubation, A. niger degraded 14% of M.O., while A. flavus and A. terreus degraded 12% of the dye.

The selectivity of greater lizardfish (Saurida tumbil), which is one of the most abundant economic species caught by gillnets in the northeast of the Oman Sea, Iranian waters, was studied. Sampling was conducted from February to March 2021. Four types of gillnets with mesh sizes of 4.8, 6.3, 10.0, and 15.3 cm were used and 857 fish specimens were collected. The catch patterns, including (snagged, gilled, wedged, and entangled) for S. tumbil were observed in gillnets. For 4.8 and 6.3 cm mesh sizes, more than 70% of the catch was mainly obtained by gilled, followed by wedged, and no found of entanglement. For 10.0 and 15.3 cm mesh sizes, the catch of 10.0 mesh size included 16% of fish caught from wedging, though most of the fish was caught by entanglement. In particular, all catches at 15.3 cm were due to entanglement. Estimation of gillnets selectivity for S. tumbil was performed using the SELECT method. The SELECT method was used to fit three various gillnet selectivity models (log-normal, skew-normal, and bi-normal). Gillnets selectivity was best estimated by a bi-modal Selection curve. The mean lengths ±SE were estimated as 31.48±0.71, 40.3±0.97, 40.1±0.75 and 43.9±1.05 cm for 4.8, 6.3, 10.0 and 15.3 cm mesh sizes, respectively. Mean lengths increased with increasing the mesh size. Most of the fish caught in the 4.8 and 6.3 cm mesh sizes were below the first maturity length (Lm50). Considering the relative efficiency set as 0.5, that was L50 (50% retention length), the optimal mesh size was determined to be 10.0 cm. Therefore, to protect S. tumbil stock and the sustainability of the fishing resource, the gillnet mesh size should be at 10.0 cm to manage S. tumbil in this area.

Carbon nanotubes (CNTs) are the most widely studied class of engineered nanoparticles due to carbon’s unique hybridization properties and they are extensively used in several fields depending on their morphology, particle size, exposure time, and concentration. These nanoparticles are released into the aquatic ecosystems through domestic and industrial wastewater and induce adverse effects on the aquatic organisms. The present study evaluated the toxicity effects of CNTs nano-particles on crustacean hyperglycemic hormone (CHH) hormone release, hematology factors, and anti-oxidative enzymes’ activity of Macrobrachium rosenbergii. This research was conducted in five treatments, including 0 (control), 5, 10, 20, and 30 mg/L CNT nanoparticles in triplicate for 28 days. The experimental units consisted of a 300-l recirculating system, stocked with, 10 prawns. The results indicated that M. rosenbergii reproductive performance, anti-oxidant enzyme activities, hematology parameters and CHH hormone release, survival rate, and growth performance were strongly affected by CNT NMs toxicity. The findings showed that SOD and CAT antioxidant enzymes activities have positive responses to the CNTS NMs in the experimental treatments and these NMs showed dose-dependent effects on the enzyme's activities. Also, CHH hormone in the experimental treatments showed significantly higher than the control treatment. The results of this work illustrate that because of the settling behavior of NMs, M. rosenbergii as a freshwater benthic decapod crustacean is an appropriate biological model to study NMs toxicity and also a suitable biomonitor for NMs contaminations in freshwater aquatic environments.

The current study aimed to determine the biochemical parameters, including glucose, total protein, cholesterol, and enzymes of AST and ALT, in freshwater shrimp Macrobrachium. nipponense after exposure to different sub-lethal concentrations of heavy metals, including iron, copper, lead, and cadmium. Samples of M. nipponense were collected from Shatt Al-Arab, Southern Iraq. The experiment was carried out in a recycling aquaculture system (RAS) consisting of plastic containers, each of 60 liters. Four different treatments were used, each treatment representing three concentrations of Iron (1.5, 2, and 2.5 ppm), Copper (0.25, 0.35, and 9.45 ppm), Lead (0.05, 0.125, and 0.175 ppm), and Cadmium (0.05, 0.1, and 0.17 ppm), in addition to the control group. The results showed a significant decrease in all biochemical parameters compared to the control one. According to the study results, AST and ALT were significantly increased compared to the control. In addition, liver enzymes and biochemical parameters are significantly impacted by heavy metals. This confirms that liver enzymes and biochemical parameters may be biomarkers to monitor heavy metal pollution.

Samples of Planiliza abu were monthly collected from Al-Mashab Marsh in the East Hammar Marsh of Iraq from January to December 2022 to study their Gonad-somatic index (GSI), hepatic index (HSI), and relative condition factor (Kn). GSI for both sexes was recorded. The highest value of GSI was 1.57 for males and 1.87 for females in March, and the lowest value was 0.27 for males and 0.70 for females in August. Based on the GSI, its spawning season is from March to April. Based on the results, the lowest value of HIS was recorded in July as 0.82 for females and in August as 0.60 for males, and the highest values were found as 1.65 in March for males and 1.87 in April for females. Kn ranged from 0.42-1.57 (males) and 0.70-1.87 (females).