Iranian Journal of Fisheries Sciences
Volume:23 Issue: 2, Mar 2024

The genus Channa has many species including several cryptic species like the great snakehead (Channa marulius), locally known as “Gajar”, distributed across its natural distribution range of Southern and Southeast Asian countries including Bangladesh. This fish needs to be conserved but there is no information regarding the morphological variations in Bangladesh. This study reveals the morphometric traits and meristic counts of C. marulius collected from the lowland ecosystem in Bangladesh. A total of 67 samples were collected from 7 locations in Bangladesh to record morphological observations. This investigation was done on 6 meristic traits and 17 morphometric features. The fin formulae of C. marulius were dorsal 55-45, pectoral 19-14, pelvic 2-6, anal 37-28, and caudal C. 17-12. The lateral line is present which continued with 68-61 scales in a single line. All relationships (coefficient of determination, r2) of the morphological measurements were found significant statistically (p≤ 0.05) by analysis of variance. The r2 value shows the length-length relationships by total length (TL) vs. standard length (SL) (TL=a+b×SL) as the best-fitted model among seventeen equations. The fifteen morphometric measurements were used for the classification of populations by discriminant function analysis and could separate the populations at p<0.001 at a highly significant level.  The principal component analysis showed that SL, TL, and LDFB (length of dorsal fin base) of the morphometric measurements were important for the phenotypic variation in C. marulius fish populations. Thus, three key characteristics can be used to know the populational variations of C. marulius in Bangladesh and these findings can be useful for making any comparisons with its related species.

Bodo Creek, like other aquatic habitats in the Niger Delta region of Nigeria, is reportedly contaminated by heavy metals due to crude oil pollution. It is unknown whether edible fishes caught from these sources pose any health risk to human consumers. The present study evaluated concentrations of arsenic (As), mercury (Hg), and lead (Pb)) in different organs of three edible fishes caught from Bodo Creek, and assessed the health risks of consuming these fishes by both children and adult populations. Samples of Ethmalosa fimbriata, Crenimugil seheli and Macolor niger were collected from artisanal fishermen fishing in Bodo Creek, and taken to the laboratory for heavy metal analysis. The results showed that concentrations of arsenic, lead, and mercury recovered from organs of these fishes differed, with gills having significantly (p<0.05) higher concentrations than muscle and liver. In terms of health risks, estimated daily intakes of Pb were higher in E. fimbriata, followed by M. niger, and the least values were recorded in C. seheli for both children and adult consumers. Target hazard quotients of these metals were below the risk level of 1 in both children and adult consumers of the three studied fishes. However, hazard index for children consumers of E. fimbriata was greater than 1. The values of incremental long-term cancer risk analysis for the studied metals were greater than the USEPA recommended safe limit of 0.000001. Based on these results, consumption of these fishes may pose future health risks for both children and adult populations.

Regional study on the status of fish communities facilitates assessment procedures and conservation measures of fishes. Therefore, the present study investigated the impact of prevailing factors on the distribution pattern and status of freshwater fish fauna from River Song in the Lower Himalaya. In nine sampling sites under three sections (upper, middle, and down), 268 fish specimens were collected, 20 fish species belonging to 4 orders, 6 families and 12 genera were identified. Barilius bendelisis and Noemacheilus rupicola (upstream), B. bendelisis (midstream), and Glyptothorax pectinopterus (downstream) section constituted a high percentage of fish composition. The upper section was a relatively less disturbed section than other sections of the River Song. The upper section had good water quality, ample riparian vegetation, and a sufficient amount of food may affect the fish communities. However, many fish populations were declined in middle and down sections due to the disturbance through anthropogenic activities (i.e., channelization, construction, and municipal wastewater) removal of vegetation in the riparian zone by local people affect the abundance and distribution of fish species. 80% of fish species have been forced into decline and need to protect their natural habitats, execute policies, and motivate people for management and conservation.

Cyanobacteria, ancient photosynthetic prokaryotes, form harmful blooms that degrade water quality and pose many risks to human health. The main objective of this study is to identify toxic cyanobacteria present in fish ponds, evaluate their effects on Zebrafish (Danio rerio) tissue, and investigate their characteristics. Samples were collected from the walls and floors of rainbow trout raceway ponds at Alborz Caspian Company, situated in Alborz province, Iran. The purpose of this collection was to isolate and examine cyanobacteria colonies. As a result of meticulous microscopic and macroscopic observations, three pure samples of Calothrix sp., Nostoc sp., and Microcystis sp. species were successfully identified. These samples were then transported to the laboratory and processed using the Z8 solid culture medium within a growth chamber. Cyanobacteria were identified based on their morphology using a light microscope and validated identification keys. The DNA extraction was performed using the cetyl-trimethyl-ammonium bromide method. Zebrafish were acclimated and fed with fish food containing lyophilized cyanobacteria for a period of 30 days. At specific intervals, fish were collected for histopathological analysis and measurement of antioxidant enzyme activity. The histopathological examination of intestinal tissue in the treatment groups exposed to lyophilized cyanobacteria revealed lesions including hyperplasia of enterocytes, reduction in their length, vacuolation of enterocytes, hyperplasia of goblet cells, and infiltration of lymphocytes. The gill samples from the treatment group exhibited severe histopathological abnormalities such as displacement of epithelial cells, fusion of lamellae, epithelial necrosis, and lymphocyte infiltration. These symptoms diminished over time. Hepatocellular lipid changes and vacuolation were observed in the treatment group's liver samples, peaking on the 30th day. The activity of superoxide dismutase (SOD) enzyme significantly increased in the exposed Zebrafish on the 30th day compared to the control group, and similar significant increases were observed on the 20th and 30th days (p<0.05). There were no significant differences in Catalase (CAT) activity between the control and treatment groups (p>0.05). Generally, the study identified specific histopathological abnormalities in the fish exposed to lyophilized cyanobacteria and observed changes in antioxidant enzymes activity. These findings contribute to understanding the impact of cyanobacteria on fish health status.

This study aimed to determine some heavy metal concentrations in the tissues of the Caspian kutum (Rutilus kutum) and Pikeperch (Sander lucioperca) as well as their parasites. The fish samples were collected from the coasts of Guilan province, Anzali port for 6 months in 2020. The fish muscle, gonad, liver, and intestine organs and their intestinal parasite samples of both fish species were collected and analyzed for Cu, Pb, Cd, and Zn concentration using the tissue dissolution technique and an absorption spectrophotometer. The results confirmed that the concentrations of Zn and Cu in the intestine and liver tissues were significantly higher than those in the muscle and gonad. Cd was not detected in the S. lucioperca tissues and its parasites, but it was detected in the liver and intestine of R. kutum. The mean concentration of Zn in Anisakis simplex parasite of R. kutum was 29.23 times higher than in the host intestine and 15.82 times higher than in the host liver. Also, Zn concentration in Rafidascaris acus (male) and Eustrongylides excisus (female) nematodes of S. lucioperca was 22.4 and 6.01 times higher than in the host intestine, respectively. The absorption rate of the four heavy metals in the muscle of R. kutum and S. lucioperca was lower than all international standards and risk index target hazard quotient (THQ) for adults and children. Pb, Cd, Cu, and Zn were not detected in the fish samples. In the contaminated fish with heavy metals, measuring the level of heavy metals in their parasites (nematodes) can also be used as an indicator for heavy metal contamination. Also, the accumulation of metals in the muscle of both fish species was lower than the world standards.

The aim of this study was to investigate the effects of dietary supplementation of a commercial probiotic containing Bacillus subtilis, Lactobacillus acidophilus, L. delbrueckii, L. rhamnosus, and L. plantarum on growth performance, hematological and immunological parameters of bester fingerlings. Two-hundred and forty fingerlings (10±0.9 g) were randomly distributed into 12 fiberglass tanks. The experimental diets were formulated using 0 (control), 100 (T100), 200 (T200), and 300 (T300) mg/kg of the probiotic. The fish were fed at 3% of body weight for 8 weeks. The result revealed that dietary probiotics increased final weight, condition factor, daily growth rate, specific growth rate, and body weight increase (p>0.05). Also, we observed a significant increase in feed efficiency ratio and protein efficiency ratio for fish fed with T300 compared to T200 (p<0.05). Hematological parameters were not influenced by dietary probiotic levels (p>0.05). There were no significant differences in total immunoglobulin (p>0.05), while alternative complement activity was significantly enhanced by the inclusion of probiotics in diets (p<0.05). The present study showed that feed efficiency, protein efficiency, and immunological parameters of bester fingerling have been improved by adding the commercial probiotic at 200 mg/kg.

The increasing use of consumer products containing nanomaterials (NMs) or utilizing nanotechnology has raised concerns about potential environmental risks associated with NMs. The toxicity of silver nanoparticles (AgNPs) in saltwater microcrustaceans, specifically Artemia franciscana, was investigated in this study. This study focused on the key factors of AgNPs concentration and exposure time. To evaluate toxicity, instar I Artemia nauplii were exposed to various concentrations of AgNPs (ranging from 0 to 10 mg/L) following the ISO/TS 20787 guideline. Immobilization rates were recorded at 12, 24, and 48 h post-exposure, and the Probit test was used for the statistical analysis. The results indicated significant toxicity to Artemia with an EC50 value of 4.18 mg/L after 48 hours. Significant relationships were found between immobility and the variables (exposure time and AgNPs concentration) through the use of multiple regression analysis for immobilization. The model explained a high percentage of immobilization variation (R-squared value: 97.74%). The study emphasizes the importance of 'exposure time' and 'concentration' in determining toxicity. The interaction effect between the parameters (concentration and exposure time) was significant. AgNPs concentration had a greater impact on increasing Artemia immobility compared to the exposure time. However, whether the same ranking applies to chronic toxicity or other organisms besides Artemia is uncertain. Understanding the relationship between exposure to NPs and their toxicity is crucial for the safe development of nanotechnology. Future research should address these questions to provide further insights and enable environmentally responsible risk assessments of AgNPs.

The sustainability and cost-effectiveness of aquafeeds are crucial research focus in the aquaculture industry. This study investigates Chaya leaf meal (CLM; Cnidoscolus aconitifolius) as an alternative to soybean meal (SBM) in climbing perch (Anabas testudineus) diet. Over a three-month feeding trial, three dietary modifications were tested, incorporating 0% (CLM 0, control group), 20% (CLM 20), and 40% (CLM 40) Chaya leaf meal. The growth performance parameters indicated no significant differences between the dietary groups (p>0.05). However, 20% CLM diet led to significantly improved survival rates (p<0.05). Detailed analysis of organosomatic indices, body composition, fillet proximate composition, hematological, and blood chemical indices demonstrated overall consistency across experimental diets (p>0.05), except for a notable variance in the crude lipid content. Likewise, digestive enzymes activity remained stable across the dietary groups. From an economic standpoint, 20% CLM diet exhibited a competitive profit index compared to the control, significantly outperforming 40% CLM diet (p<0.05). These findings support the viability of 20% CLM as a partial substitute for soybean meal in climbing perch diets, providing environmental and economic advantages. Nevertheless, additional research is essential to determine the optimal CLM inclusion level and understand its long-term impact on fish health and productivity.

The great amount of unutilized rest raw materials in the cartilaginous fish industry led to investigate the possible utilization methods to generate a value-added product. In this study, the residual aqueous fractions of oil extraction processes from the liver of longnose ray (Zearaja flavirostris), were evaluated as a possible replacement for the commercial yeast extract peptone dextrose (YPD) culture medium for Saccharomyces cerevisiae. Oil extraction from the ray livers was carried out by different processes such as enzymatic hydrolysis, cold extraction, and extraction by applying high temperatures. The obtained culture media based on the aqueous fractions from the fish ray livers were compared with an industrial reference media. The pattern of cell growth and biomass yield was similar using both the standard culture medium for YPD as a positive control and the diluted and supplemented with the aqueous fractions obtained by the enzymatic extraction method. The results suggest that these by-product fractions provide an alternative source of carbon (peptides and free amino acids) as well as macro- and microelements for the growth of S. cerevisiae.

In this paper, both of growth and size structure of a population of C. fossarum are studied for the first time. The average sizes of females were significantly higher than those in males (P<0.05). Proportions of morphological characteristics to carapace length in male were significantly higher than those in females (P<0.05). No difference was detected between the ratio of RL/CL of both sexes (P>0.05). The size frequency distribution was normal for either sex, with a peak of occurrence in the size classes 5, 6 and 7 (4.0-5.5 mm). In females the growth rate of TL in relation to CL was greater than males and constant (isometric growth) in spring and summer, while in males a decreasing rate (negative allometric) in each two seasons of year was observed. Therefore, as expected, the growth rate of W in relation to CL for female sex was greater in spring and summer. Condition factor was higher in female shrimps (1.56) than males (1.52) (P > 0.05). On monthly based analyses, variations in the condition factor were similar for both sexes, and minimum value was observed in winter. Asymptotic length (L∞), growth rate (k) and maximum life span estimated of males were 6.1 mm, 0.61 per year and 3.43 years; those for females were 6.62 mm, 0.71 per year and 3.17 years respectively.