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This study aimed to evaluate the lethal toxicity of chlorpyrifos and its effect on food consumption, oxygen consumption rate, ammonia excretion rate and O: N ratio of P. hypophthalmus fingerlings. The acute bioassay test was performed by adopting the static renewal method. Results showed that the median lethal concentration (LC50) of Chlorpyrifos for 96 h was 0.1060 mg L-1. One-fifth T1 (0.0212 mg L-1) and one-tenth T2 (0.0106 mg L-1) of LC50 values were selected for sublethal studies for 45 days revealed that the food consumption rate, oxygen consumption rate and O: N ratio decreased significantly (p<0.05), while ammonia excretion rate increased significantly (p<0.05) at both the concentrations as compared to control. The results obtained in this study proposed that measurements of food consumption rate, oxygen consumption rate, ammonia excretion and O: N ratio can be useful as a stress indicators of P. hypophthalmus fingerlings. [ABSTRACT FROM AUTHOR]

Amazon sailfin catfish are native to Latin Arica (Siluriformes: Loricariidae: Pterygoplichthys) and are popular around the world as ornamental fish. It is well-documented that these species are highly successful invaders and very prone to forming new geographical ranges. However, once established, eradicating a new population is a very challenging task. In Bangladesh, species of the genus Pterygoplichthys are expected to spread widely and have a severe detrimental impact on ecosystem health, biodiversity and economics. Here we provide new information on the future probable establishment of non-native populations of these species in the wild using a climate-matching analysis and highlight their potential area of occurrence. The potential socio-economic consequences are also discussed, as are the public perception of these species and probable economic damages caused. Control of the import of similar species, their culture and intentional or unintentional release into open water is urgently required. [ABSTRACT FROM AUTHOR]

Objective: Bacterial community profiling in aquaculture can be useful for monitoring environmental conditions that may lead to disease outbreaks, understanding the impact of dietary treatments on fish health, and identifying microbes that have potential as probiotics. Microbiota characterization is commonly performed with high‐throughput sequencing using short‐read platforms (i.e., Illumina) targeting variable regions of the bacterial 16S ribosomal RNA (rRNA) gene. Long‐read platforms (i.e., Oxford Nanopore Technologies [ONT]) enable sequencing of full‐length 16S rRNA genes. While short‐read platforms are highly accurate, long‐read platforms sacrifice sequence quality in exchange for longer read lengths. Methods: Herein, a typical short‐read approach (Illumina MiSeq; V4 region of 16S rRNA gene) was compared with two near‐full‐length 16S rRNA gene ONT protocols (ONT Custom and ONT 16S). Sequencing was performed on a mock community composed of fish‐relevant bacteria, in addition to samples (digesta, gill, skin) obtained from 10 hybrid catfish (female Channel Catfish Ictalurus punctatus × male Blue Catfish I. furcatus) and their environment (pond and holding tank). Fish were euthanized with either an overdose of MS‐222 or cranial concussion and subsequent pithing to enable comparisons of these sequencing protocols in the context of a realistic experimental design. Result: The ONT Custom protocol best recapitulated the theoretical composition of the mock community, followed by the ONT 16S and Illumina MiSeq protocols. Phylum‐level composition was consistent within sample type across sequencing methods. However, at lower levels there were biases for several taxa, particularly in pond samples. Euthanasia method also appeared to introduce differences, primarily on the cutaneous communities. The three sequencing methods consistently identified significant differences between euthanasia methods, with Illumina MiSeq revealing the greatest differences. While all strategies performed comparably for digesta, skin, and water samples, the ONT strategies underperformed for gill samples. Conclusion: Depending on application, results indicate that near‐full‐length 16S rRNA gene nanopore sequencing is a viable option for aquaculture microbiota studies. Impact statementIn this study, we found nanopore sequencing of catfish‐related samples was a viable approach for characterizing bacterial populations. Utilizing a mock community composed of known amounts of bacterial DNA, we were able to evaluate how accurate each protocol was. These results provide valuable information to aquaculture researchers conducting bacterial community profiling studies. The methods described can be used in future studies to evaluate the effects of various treatments and environmental factors on fish and pond bacterial communities, allowing for an improved understanding of aquaculture management practices on the fish microbiota. [ABSTRACT FROM AUTHOR]

Striped catfish, Pangasianodon hypophthalmus is a native species to most Asian countries, including Malaysia which faced series of bacterial disease such as edwardsiellosis caused by E.ictaluri. Edwardsiella ictaluri is a Gram-negative intracellular bacterial pathogen which had caused mortalities in farmed or wild fish in lots of countries and accountable for large economic losses. This study was conducted to determine disease status of Pangasius spp due to Edwardsiella ictaluri and to determine the risk factors of E.ictaluri in striped catfish in Pahang River, Malaysia. Four sampling sites were chosen, two sites in Pekan (Kampung Belimbing and Kampung Tanjung Pulai) and two sites in Temerloh (Kampung Teluk Ira and Kampung Bintang). Thirty samples were collected from each farm for 6 months consecutively and four organ tissues were taken which were liver, spleen, kidney, and brain. External and internal clinical signs were recorded accordingly. DNA was extracted from all tissues and pursued for PCR to detect the presence of Edwardsiella ictaluri. Results show that the infected fish has gross internal clinical signs such as patchy liver, white nodular spleen, and congested kidney. The prevalence rate of E.ictaluri was highest at Kampung Tanjung Pulai in June with 16.67% compared to all farms. No infection of E.ictaluri shown at Kampung Belimbing during the whole sampling session. Spearman's rho correlation showed that the prevalence of E.ictaluri has strong correlation with temperature in Kampung Tanjung Pulai (p > 0.05). Meanwhile those bacteria prevalence have strong relationship with ammonia, sulfide and total suspended solid (TSS) with p< 0.05. The susceptible size for this bacterium in striped catfish is between 1 to 50g. To our knowledge, this paper is the first report for Edwardsiella ictaluri in cage cultured P.hypopthalmus in Pahang River, Malaysia. [ABSTRACT FROM AUTHOR]

This study focuses on pathogenicity and LD50 of Pangasius nasutus against Edwardsiella ictaluri. Pangasius nasutus or 'patin buah' is a native freshwater species of peninsular Malaysia and can be found in Pahang River. The market price for this species is high as it tastes better compared to other catfish. Edwardsiella ictaluri is a pathogenic bacteria and the causative agent that cause enteric septicemia of catfish (ESC) in the Pangasius species. However, the prevention measures against Edwardsiella ictaluri are still unknown for Pangasius nasutus due to the lack of research and study. Therefore, the objective of this study is to identify Edwardsiella ictaluri isolated from Pangasius nasutus cultured in Pahang River using polymerase chain reaction (PCR) and to determine the pathogenicity and LD50 of Pangasius nasutus against Edwardsiella ictaluri through injection method. There are four different concentrations of Edwardsiella ictaluri (1×1020, 1×109, 1×108, 1×107) that were injected intraperitoneally including normal saline water as control to a total of 50 Pangasius nasutus. Observation of clinical signs and mortality were carried out for 30 days and LD50 was determined. The earliest clinical sign was observed at concentration of 1×1010 cfu/ml at 2 hours postinfection of Edwardsiella ictaluri where pale liver and congested kidney can be observed after dissection. Other clinical signs observed are inflammation on tail and fin, hemorrhagic fin, hemorrhagic upper mandible, discoloration, and inflammation on the lower part of body. The first mortality of Pangasius nasutus was at concentration 1×1010 cfu/ml at 2 hours of post infection. The highest cumulative mortality was recorded at concentration 1×1010 cfu/ml with 100% of mortality rate. From the result, the value of LD50 of Edwardsiella ictaluri calculated was 1×106 cfu/ml. From this study, it can be concluded that Edwardsiella ictaluri does affect the survivability Pangasius nasutus in Malaysia. [ABSTRACT FROM AUTHOR]

Contamination by microplastics (MPs) has been recorded in various environments and organisms around the world. The objective of this study was to investigate the occurrence of MPs in two species of Siluriformes fishes Pterygoplichthys pardalis and Hoplosternum littorale considering the sex and different body parts of fish captured in Amazon floodplain areas, which are marketed and consumed in the Municipality of Itacoatiara, Amazonas, Brazil. One hundred and fifty individuals of each fish species were analyzed for microplastics. Of these, 252 individuals were found to contain MPs: 127 (85%) P. pardalis and 125 (83%) H. littorale. The fish were contaminated with 683 MP particles, ranging from 1 to 43 MP particles/individual, with an average of 2.71 ± 3.2 MP particles/individual P. pardalis and H. littorale. Comparison of MP occurrence and particle size between species, sex, and body part found no significant difference. Fiber-shaped and blue-colored MPs were the most abundant in both P. pardalis (80% and 85.5%, respectively) and H. littorale (92% and 85%, respectively). The particles were identified as polyethylene terephthalate and polystyrene. The results indicate MP contamination in P. pardalis and H. littorale catfish, which are widely consumed by Amazonian riverside communities. These species are often cooked whole (including the viscera) becoming a direct route of microplastic contamination to humans. [ABSTRACT FROM AUTHOR]

The effect of different concentrations of Chromolaena odorata (Siam weed) supplementation in fish feed on Clarias gariepinus fingerling growth characteristics was examined. Fish were randomly assigned to one of the four experimental groups: 0.0 percent (controls), 0.5 percent, 1.0 percent, and 3.0 percent concentrations of Chromolaena odorata in feed. Fish was fed at 5 percent body weight (g) per day for 70 days. Results showed that fish-fed the treatment diet had no significant effect on weight gain. The final body lengths (cm) of all treated groups were marginally (P > 0.05) different from the control group after 70 days. When the growth parameters were considered, the fish fed the diet containing 1.0 percent Chromolaena odorata had the best growth response (2.4±0.04g) while the fish fed the control diet had the slowest growth (1.2±0.13g). In comparison with the control fish fed the diet containing 1.0 percent Chromolaena odorata had the best feed conversion ratio (FCR), specific growth rate (SGR), and condition factor (K) This study showed that the inclusion of Chromolaena odorata in fish food at 0.5 - 3.0 percent level did not significantly increase the weight and length of catfish. [ABSTRACT FROM AUTHOR]

The objective of this research is to assess the length-weight relationship (LWR) as well as Fulton's condition factor of freshwater catfish species i.e., Rita rita from Gomti River, Lucknow, Uttar Pradesh. A total of 319 fish specimens were randomly sampled from January 2022 to December 2022. The results revealed the values of 'b' for male, female, and pooled populations are 2.68, 2.73, and 2.70 respectively which represents negative allometric growth. The coefficient of correlation, 'r²' between total length and body weight for males, females, and pooled population were estimated as 0.931, 0.934, and 0.933 which is significant at a 1% level. The fish were found to be in good health condition, as the calculated value of Fulton's condition factor varied from 1.33 to 1.39. The present research is beneficial as it offers pertinent data for studying fish biology, assessing the condition of fish in their habitat, and evaluating parameters about population dynamics.² [ABSTRACT FROM AUTHOR]

Opisthorchis pedicellata (Verma, 1927) a common trematode parasite was recovered from the gallbladder of the freshwater catfish species Rita rita (Ham.) from Gomti riverine ecosystem of Lucknow, India. The study is focussed on the seasonal and monthly variation in helminth infection represented by parameters like prevalence % and Mean Intensities. This is assessed for the fluke Opisthorchis pedicellata that was recovered from the catfish Rita rita for two annual cycles (July 2021 to June 2023). A total of 840 Rita rita fish were randomly collected from local fisherman from Pipraghat of Gomti river, Lucknow. The fishes were dissected for investigating the parasitological presence of fluke Opisthorchis pedicellata. Presence of the fluke was recorded throughout the study period but in varying intensities and seasonal cycle of occurrence. The prevalence% ranged between 37.43% to 71.43%. In the month of August 2022, 71.43% of the total examined fishes were found infected with the fluke. The prevalence% was least during the month of December 2021 when only 37.43% of the fishes examined were found infected. The maximum mean intensity was seen in the month of July 2022 while the minimum was observed during the month of February 2022. [ABSTRACT FROM AUTHOR]

Even though several studies have reported how stress induces detrimental pathophysiological responses that are linked to increase in disease susceptibility, no study has evaluated the impact of overcrowding on the serum chemistry of Heterobranchus longifilis. This study aimed at evaluating the impact of overcrowding on serum chemistry in Heterobranchus longifilis. Briefly, 30 apparently healthy Heterobranchus longifilis weighing between 1 kg and 1.5 kg were randomly divided into 2 groups of 15 catfish, each designated as groups 1 and 2. Group 1 (control group) was not subjected to stress, while group 2 was subjected to 3 hours of overcrowding in a 120 L plastic water tank at 201 g/L of water. Blood samples were collected from the caudal vein into non-heparinized tubes before stress, immediately after stress and 24 hours after stress. Sera were collected, and serum chemistry and electrolytes were analyzed. At 24 hours after stress, alanine aminotransferase, alkaline phosphatase, aspartate aminotransferase, creatinine, uric acid, total bilirubin, conjugated bilirubin, total protein, albumin, total cholesterol, triglyceride, chloride, potassium, and sodium were significantly higher in group 2 compared to the control group. Based on the findings of this study, it was concluded that overcrowding of Heterobranchus longifilis for 3 hours has a significant impact on its health status. [ABSTRACT FROM AUTHOR]

The technical efficiency of the African catfish production in Nigeria was assessed. A total of 609 farms were sampled, and 1,118 operations were recorded covering both the pre-COVID and COVID periods. A translog stochastic frontier modeling approach was used to simultaneously assess the technical efficiencies and the determinants of technical inefficiency of the catfish farmers. The mean technical efficiency for the catfish production in Nigeria is 85.4% indicating a scope of increasing production by 14.6% given the current technological state, which could contribute an additional 42,273 metric tons of fish to Nigeria's aquaculture. Comparative analysis showed that catfish producers during the COVID-19 period and producers from the Southern region were more technically efficient. The effect of management-dependent determinants is presented. Beyond management approaches, technical efficiency is seen to be improved significantly through the use of quality inputs. Based on these, measures for successful catfish production in Nigeria are recommended. [ABSTRACT FROM AUTHOR]

This study examined the cost efficiency of catfish production under different systems in Delta State, Nigeria. Primary data collected from 360 catfish farmers (comprising 121 concrete pond, 99 earthen pond and 140 plastic/tarpaulin pond systems) provided useful information for the data analysis. Descriptive statistics were used to describe the socioeconomic characteristics of the respondents. The stochastic cost frontier (SCF) approach was employed in analyzing the effi- ciency indices and their determinants. The results showed that the respondents were male dominated (64.44%), young and active, with the majority below 48 years of age. The majority of the respondents (76.67%) had a form of education that could boost their managerial abilities for catfish production. About 67.50% farmers were working full-time and 38.89% of them adopted the plastic/tarpaulin pond method because of ease of management. The average catfish weight produced was 1.50kg, and the average price per kg of mature catfish sold was NGN ₦ 722.77, with an average cost efficiency of 0.70. The study concludes that catfish production under different production systems is a cost efficient and economically viable venture, with the earthen pond method the most cost ef- ficient (0.72). The study therefore recommends that the causes of inefficiencies should be considered and addressed so as to enhance the efficiency of catfish farmers. [ABSTRACT FROM AUTHOR]

Invasive suckermouth armored catfish Pterygoplichthys spp. successfully spread during one decade into many river systems of Vietnam. Wide and rapid invasion of armored catfish might be associated with using brackish water in estuaries to spread from one river system to another. The first goal of our study was to assess the horizontal and vertical distribution of invasive fish in freshwater (Da Rang River) and in brackish water (Da Rang River estuary) associated with circadian rhythm. In the both sampling locations, fish were mainly caught at nighttime at the bottom and near the surface using the net traps and vertical nets. In estuary, fish were caught in the net traps with distance 2.0–7.5 m from the right or left banks where water was predominantly fresh. In freshwater of the Da Rang River, fish were often caught near the left bank with gravel and stone substrate. The second goal of our study was to experimentally evaluate the circadian (12 hours of the night and 12 hours of the day) rhythm of locomotor activity (LA) of fish. Fish from different freshwater locations (Am Chua canal and Da Rang River) had a similar diurnal dynamic of LA with mostly movements (77–83% of total diurnal LA) at nighttime (18:00–6:00, GMT+7) at the end of the wet season. Armored catfish from the brackish water location (Da Rang River estuary) also were mostly active (76% of total diurnal LA) overnight. However, fish from freshwater and brackish water had difference in the timing of behavioral activity. Fish LA from estuary was significantly lower than LA of fish from freshwater locations during 18:00 to 21:00 before low tide. The results of our field and experimental studies established that armored catfish in estuary moved in horizontal and vertical planes predominantly at nighttime. Tide level regulates locomotor activity of invasive fish and could influence on the possibility of their spreading through the estuary. [ABSTRACT FROM AUTHOR]

In vertebrates, insulin-like growth like factors (IGFs) play an important role in growth and other physiological processes. The GH-IGF axis is considered a valuable tool to monitor fish growth performance. Herein, we report the molecular characterization of igf-1, igf-2, and β-actin transcripts and relative expression of igf-1 and igf-2 in the liver and muscle tissue of cage-reared butter catfish, Ompok bimaculatus, in response to different stocking densities (T1, 15 fingerlings m−3; T2, 25 fingerlings m−3; and T3, 35 fingerlings m−3) over 180 days of culture duration. The length of the partial amplified transcript sequence of Obigf-1, Obigf-2, and Obβ-actin was 325, 438, and 924 bp, respectively. Phylogenetically, Obigf-1 and Obigf-2 were closely clustered with catfishes, viz., Clarias magur, Bagarius yarrelli, and Silurus asotus. The expression of igf-1 was significantly downregulated in the liver at higher densities after 120 days as biomass in the cages increased, while igf-2 expression did not change with the stocking densities over the culture period. Cortisol concentration was significantly elevated in T3 groups post 150 days of the culture period and correlated negatively with the expression of igf-1 (p < 0.05) and igf-2 (p > 0.05). Environmental parameters, pH, TDS, hardness, conductivity, and alkalinity showed a significant positive correlation with hepatic IGF expression. Our study indicates that the liver-derived igf-1 plays a more important role in the regulation of growth in response to culture density in the species studied, and thus, igf-1 can be used effectively as a biomarker for growth. Furthermore, this study will help in planning a proper harvest schedule and optimize the culture practices of O. bimaculatus in an open water cage system. [ABSTRACT FROM AUTHOR]

Background: Water pollutants cause adverse effects in aquatic ecosystems. The immunomodulatory and mitigating effects of dietary 1,3-glucan on fipronil and lead-induced intoxication in African catfish (Clarias gariepinus) were investigated. Two hundred forty catfish were randomly divided into four equal groups: those in the first group were fed basic diet and served as controls; those in the second group were supplemented with β-1,3-glucan (0.1%); those in the third group were exposed to combination of lead nitrate at 0.041 mg/L (1/10 96 h LC50) and fipronil at 2.8 mg/l (1/10 96 h LC50); and those in the fourth group were exposed to combination of fipronil, lead, and β-1,3-glucan. The health status, haematological, immunological, and histological changes were all evaluated. Result: Swelling on the dorsolateral side, spinal column deviation, sluggish movement, skin bleaching, excessive mucus secretion, significant variations in blood indices-related measures, and a 45% death rate were observed in the third group. There was a significant reduction in interleukin-1 (IL-1) and interleukin-6 (IL-6) and immunoglobulin M (IgM) concentrations, as well as decrease in their corresponding gene expression, indicating that fipronil and lead had immunosuppressive activity. Severe catarrhal enteritis and mucinous degeneration of the lining epithelium, and notable depletion of white pulp, congested red pulp and hemosiderosis were common pathological findings in the spleen. β-1,3-glucan alone or in combination with fipronil and lead provoked physical activity, blood indices, with elevations in IL-1β, IL-2, IL-6, and IgM concentrations, as well as up-regulation in their genes' expression in splenic tissues, when compared to the third group. The spleen and intestine had normal histological architecture with 5% mortalities. There were no fish deaths in the β-1,3-glucan-alone or control groups. Conclusion: The use of β-1,3-glucan (0.1%) as dietary supplement could be implemented to protect against the toxic effects of fipronil and lead toxicity by improving the health and immunological parameters of intoxicated catfish. [ABSTRACT FROM AUTHOR]

Striped catfish is one of the most important farmed fish species in Vietnam but often susceptible to hemorrhagic septicemia caused by Aeromonas hydrophila. Phage therapy is a promising solution alternative to antibiotic usage due to the bacterial antibiotic resistance. In this study, five individual factors including molasses concentration, KH2PO4 concentration, yeast extract concentration, bacterial culture time and phage collection time were investigated for their effects on the producion of phage TG25P. Plackett-Burman design revealed that the bacterial culture time, phage collection time and molasses concentration were the most significant factors affecting the phage production. Application of response surface methodology for optimization of phage production showed that optimal values for these variables were 1.76 h, 2.22 h and 2.03 g/L, respectively. In the optimized medium, the phage production of (1.44 ± 0.2) x 109 PFU/mL was obtained, which agreed well with the predicted value of 1.37 x 109 PFU/mL. The findings really help us produce phage TG25P under the optimal condition at a low cost. [ABSTRACT FROM AUTHOR]

Trichodinosis, an ectoparasitic infestation caused by ciliated protozoa-Trichodina spp., is commonly found in skins and gills of freshwater fishes and causes a significant economic loss of fish farming. Synthetic chemicals are widely used to eliminate trichodinosis but it poses a potential risk to environment. The aim of this study is to develop of a new alternative approach by using a natural and environment-friendly material, such as bead tree (Melia azedarach L.) leaf extract for treatment of trichodinosis in whitespotted freshwater catfish (Clarias fuscus). The ethanol leaf extract (EtMA) was obtained via ultrasonic assisted extraction (30 °C, 90 min). The preliminary phytochemical screening confirmed the presence of some bioactive compounds in the extract, including alkaloids, tannins, saponins, phenolic compounds, steroids, terpenoids and flavonoids. In the in vitro experiment, all of doses of the extract (50, 100, 150 ppm) could effectively eradicate Trichodina nigra after 180 min of treatment (53.03 %-85.35 %). The extract showed no acute toxicity to whitespotted freshwater catfish after bath treatment up to 1,600 ppm for 15 min. The trichodinosis model was established via infection of Trichodina nigra in whitespotted freshwater catfish and bath treatment with EtMA (800, 900, 1,000 ppm) not only decreased the infection rate of T. nigra (20.00 %-46.67 %) but also enhanced the survival rate of T. nigra infected fishes (56.67 %-90.00 %) as compared to untreated fishes. The hematological (red blood cells, white blood cells, and hemoglobin) and biochemical parameters (total protein, blood urea nitrogen, creatinine, and total bilirubin) of all doses of EtMA-treated fishes were improved as compared to those of untreated fishes. These findings suggest that EtMA has potential use as a green and natural treatment to control trichodinosis in whitespotted freshwater catfish farming. [ABSTRACT FROM AUTHOR]

Glyptosternoid fishes are distributed in the torrent environment of alpine canyons, where they often leave the water to climb rocky cliffs. As one of the most primitive species of glyptosternoid fishes, Euchiloglanis kishinouyei was examined in the current study to analyse its gill microstructure and respiratory ability. We first found that the oxygen consumption rate was relatively high and negatively correlated with body mass and that the average oxygen consumption at night was higher than during the day. The asphyxiation point of E. kishinouyei (5.05 ± 0.22 g) was c. 1.93 mg/L. Subsequently, the surface morphology, gross gill tissue structure, and ultra‐microstructure of gill lamellae were investigated using optical microscopy and SEM. The gills showed an overall trend of regression, with five pairs of gill arches in each gill cavity. The adjacent gill filaments had large gaps, and the gill lamellae were thick. The gill filaments were closely arranged on the gill arches, their folded respiratory surface was highly vascularized with no tiny crest, and there were obvious tiny crests, grooves, pits, and pores on the nonrespiratory surface. The gill lamellae were closely embedded on both sides of gill filaments, which were composed of flat epithelial cells, basement membrane, pillar cells, and mucous cells. The gill total respiratory area correlated positively with body mass and length, whereas the gill relative respiratory area correlated negatively with body mass. We comprehensively analysed the gill microstructure and respiratory capacity of E. kishinouyei to provide fundamental data for the adaptive evolution of the gill structures of bimodally respiring fishes and offer insights into further study on the accessory air‐breathing function of skin. [ABSTRACT FROM AUTHOR]

On the Mekong River, north of Stung Treng town in northeastern Cambodia, and below the border with Laos, lies an area of riverine seasonally flooded forest designated as an internationally significant Ramsar wetland site because of its exceptional biodiversity and importance to livelihoods. This article reports on the cumulative and cascading impacts of numerous upstream hydropower dams in China and Laos on this vital ecosystem due to the release of water during the dry season, which prevents the flooded forest from undergoing its critically important drying out period. In particular, we investigate the damage being wrought on these flooded forests and on the various species dependent on them. Different species have been variously affected, but some have been largely destroyed. Others are being increasingly impacted. This habitat loss is negatively affecting fisheries, especially for a number of Pangasiidae catfish and Cyprinid carps, which is having an adverse effect on local livelihoods. New dams upriver, and continued high dry-season water from existing dams, are likely to lead eventually to the increased degradation and possibly the eradication of the flooded forests along the mainstream Mekong River, unless measures are taken to address the problem. [ABSTRACT FROM AUTHOR]

The anatomy, growth, and differentiation of the dorsal fin spines of three catfish species collected from the Nile River and Lake Nasser. Egyptian waters are described, and terminology is suggested for their parts. Features of the dorsal fin spine that change with growth are also described. The results showed that in all species studied, the dorsal spine is an elongate, compressed, tapered, slightly arched, osseous structure, bearing a series of retrorse dentations along the anterior and posterior surfaces and has a sharp sagittate tip. The retrorse, anterior dentations are most pronounced in the upper third of the spine and gradually alter in form until they appear as a series of distinct notches on the basal third of the spine. The anterolateral surfaces of the dorsal spine are marked by numerous short, irregular, shallow, anastomosing, longitudinal furrows. In three species (C. auratus, S. schall, S. serratus), the posterior process is poorly developed and directed laterally in young individuals and well produced and directed posteriorly in older specimens. In S. schall and S. serratus, the posterior blocking process of the large specimens has a wavy edge, while in S. serratus, it is curved in young individuals and straight in larger specimens. [ABSTRACT FROM AUTHOR]

Artificial light in various spectral is a relatively new development for modifying the environment of fish. According to research, light has a spectral and species-specific effect on fish.. As a result, the goal of this study was to see how different visible light colors affected Clarias gariepinus growth and digestive enzymes. 105 Juvenile fish (body length 10.00 ± 0.55 cm, initial weight 8.67 ± 0.62 g) were randomly exposed in triplicate to the following LEDs: Red (RL), Blue (BL), Green (GL), and Yellow (Y). Total Darkness (TD) and Ambient Light (AL) were used as controls. The fish were exposed for 12 hours overnight for 50 days. At five-day intervals, the fish's body weights were measured with an electric weighing scale (0.01g sensitivity); head length (cm), tail length (cm), and total body length (cm) were measured with a graduated measuring plastic box. The variables listed below were computed: Weight Gain (WG), Daily Weight Gain (DWG), Daily Growth Rate (DGR), Specific Growth Rate (SGR), Percentage Weight Gain (PWG), Food Conversion Ratio (FCR), Length Gain (LG), Daily Length Gain (DLG), Survival Rate (SR) and Condition Factor are some of the metrics used to calculate weight gain. Standard methods were used to measure the activities of digestive enzymes (proteinase and amylase). ANOVA was used to compare the acquired means, and Duncan's multiple range tests were used to further separate the means. Fish reared in YL had significantly higher WG, DWG, DGR, PWG, DLG, LG, and CF levels. SR of fish reared under TD conditions was the lowest, but it was significantly (P < 0.05) higher in fish reared under YL and RL conditions. Fish exposed to YL had significantly higher FCR and CF than those exposed to the other light treatments and the Control. The digestive enzyme activities were significantly (P < 0.05) reduced during the light treatment. Finally, nighttime artificial light exposure had a significant impact on juvenile catfish growth performance and digestive enzymes, with yellow light eliciting better growth performance. [ABSTRACT FROM AUTHOR]

Resource partitioning is essential for coexistence of phylogenetically related species in altered environments, where changes in biotopes can limit resources and change ecological strategies. We investigated resource partitioning between two congeneric catfishes (Hypostomus affinis and H. luetkeni) in three niche dimensions (trophic, spatial, and temporal) in a Neotropical reservoir. We tested the hypothesis that the use of different mesohabitats (spatial dimension) is more relevant for the coexistence of species, and that morphological differences between the species confer different advantages in the mesohabitats occupation. We evaluated species morphology, diet composition and abundance along a spatial-temporal gradient. A high dietary overlap and a low temporal variability in species abundance were found, indicating that these two dimensions play a minor role in the species distribution. However, a strong spatial segregation modulated apparently by morphological differences was observed. Hypostomus luetkeni has a larger oral disk area, and a flatter body that confer advantages in the occupation of lotics habitats, whereas H. affinis has relatively larger fins that provide more efficient displacements in lentic habitats. Spatial partitioning was the main driver modulating mechanism for the coexistence of these species and differences in the occupation of the mesohabitats probably have been amplified in this altered environment. [ABSTRACT FROM AUTHOR]

The studied fish remains come from the excavations carried out by the Ștefan Honcu archaeologist between 2017 and 2020 within the Argamum archaeological site. The study methodology consisted mainly of anatomical and taxonomic identifications based on archaeozoological atlases, quantification of the data, taphonomical evaluation, osteometry, size and weight estimation, and energy yield estimation. The archaeozoological material represents food waste. The only osteological remains registered with butchering marks was a fragment of a caudal vertebra from Silurus glanis (catfish). The studied material consists of 72 fish remains coming from carp – 28 fragments, catfish – 19 remains and the rest of 25 fragments couldn`t be identified up to species level. The faunal material is dated as follows: second half of the V century level – 9 remains, 4 remains from carp, a fragment from catfish and 4 fragments from unidentifiable fish; first half of the VI century - 17 osteological remains coming from carp – 7 remains, catfish – 8 remains and two unidentified fragments; second half of the VI century were discovered the most fish remains – 41 osteological fragments; late VI – early VII century - 5 fragments, 2 remains coming from carp and 3 remains from catfish. Most of the carp individuals range between 60-80 cm and 80-100 cm. For catfish, most of the individuals have sizes between 220 -240 cm. Based on the estimated amount of meat for each species, the energy yield (kcal) was calculated, the assemblages dated to the VI century being the richest. [ABSTRACT FROM AUTHOR]

Background: Catfish is a freshwater and saltwater fish type with a wide distribution throughout the Indonesian archipelago. This study was conducted to analyze Indonesian catfish's genetic diversity and evolutionary relationships based on the mitochondrial ND6 gene. Methods: Twenty-eight catfish samples were collected from nine rivers and one ocean in seven provinces of Indonesia. The MT-ND6 gene was amplified by using a set of primers (BaungND6F and BaungND6R). The MEGA X software was used to examine the MTND6 sequences for genetic variation and phylogenetic relation between Indonesian catfish populations. Result: There were 167 nucleotide site variations and thirty-two amino acid variations in the MT-ND6 gene. The genetic difference among populations ranges from 0.9 to 25% and the average evolutionary divergence in the overall populations was 14%, with catfish BB and PM having the closest genetic distance, while the farthest is BF to MP and BF to MS. In conclusion, the phylogenetic tree indicated that there were four distinct catfish clades in this study: MP, MS, KR, PM, BB and KS had been grouped with Hemibagrus nemurus (Bagridae family), EM had been grouped with Mystus vittatus (Bagridae family), BSBJ had been grouped with Pangasius pangasius (Pangasiidae family) and PD and BF had been grouped with Netuma thalassina (Ariidae family). [ABSTRACT FROM AUTHOR]

Background: Skin is one of the abundance side products of the striped catfish (Pangasius hypophthalmus) fillet industry in tropical countries. The previous histological study revealed that the skin of striped catfish contains high collagens which has the potential to supply the increasing halal gelatin demands. However, the texture of striped catfish skin gelatin (SCSG) at room temperature is mushy. This can be enhanced by the transglutaminase (TG) modification. SCSG modified with TG (SCSG_TG) needs to be tested for safety and consumer acceptance before being marketed. The research aims to decide the level of acute toxicity of SCSG_TG in mice (Mus musculus) and discover the organoleptic quality of SCSG_TG. Methods: Striped catfish skin gelatin modified with transglutaminase (SCSG_TG) was acquire by CH3COOH (acid) and NaOH (base) extraction at a temperature of 58°C. Toxicity tests using mice were worked by the Limit Test Procedure of the Organization for Economic Cooperation and Development (OECD) and then analyzed descriptively and qualitatively. While organoleptic tests were worked using hedonic assessment and the Friedman test. Results: The result shows SCSG_TG did not induce any toxic effects or death in mice. SCSG_TG 10 mg film was the most favored treatment group by the panelists (4.9-6.5) compared with SCSG_TG 0 mg (3.8-6.0) and SCSG_TG 50 mg film (4.1-6.3). Conclusion: Hence, the striped catfish skin gelatin film modified with transglutaminase (SCSG_TG) was declared safe, non-toxic, and accepted according to the organoleptic assessment that has met the standard ("dislike" criteria <25%). [ABSTRACT FROM AUTHOR]

Objective: Proliferation of consumer‐grade live‐imaging sonar (LIS) has created management challenges in recreational fisheries. Most pervasive is the question about whether LIS users catch fish more effectively than nonusers. This project was designed to elucidate the effects of LIS use on catch of Blue Catfish Ictalurus furcatus from the Milford Reservoir, Kansas. Additionally, we sought to identify angler perception of LIS and quantify differences in angling behavior between users and nonusers. Methods: We organized a Blue Catfish angling experiment where 16 anglers used LIS and 16 anglers did not. The experiment was followed by dissemination of a survey to measure angler experience and skill, measure perception of LIS, and identify behavior patterns from groups that did and did not have access to the technology. A multivariate linear model was used to identify how LIS use, angling experience, and self‐assessed angling skill influenced fish catch. Comparisons of LIS perceptions and angling behavior were also evaluated between treatment groups. Result: There was no difference in Blue Catfish mass captured per 5‐h angling trial by anglers using LIS (mean = 14.57 kg, SE = 3.38) and anglers not using LIS (mean = 16.97 kg, SE = 2.29). However, self‐rating of angling skill was identified as a predictor in a supported model but little variation in catch was explained (R2 = 0.169). Anglers using LIS thought their time spent searching and catch would have been similar if they did not use LIS. Anglers that did not use LIS thought they would spend more time searching for fish and catch may have increased if using LIS. Time spent searching for angling locations was greater for anglers using LIS than those not using LIS. Conclusion: Results from this study suggest that the use of LIS may influence Blue Catfish angler perception and behavior more than catch. Impact statementAngler catch of Blue Catfish was not influenced by live‐imaging sonar in this controlled experiment. However, there was evidence that the use of live‐imaging sonar influenced angler perception and behavior. [ABSTRACT FROM AUTHOR]

Objective: Suckermouth armored catfishes (SACs; Loricariidae) have invaded water bodies outside their native range globally. Population control methods, including removals and genetic biocontrols, may be enhanced through greater knowledge of sex discrimination, sex ratios, and potential sex bias among control methods. Methods: We investigated sexual dimorphism and population sex ratio for an invasive SAC population of Hypostomus sp. in the upper San Marcos River, Texas, USA, as a means of advancing ongoing management of the population. Result: Among 385 specimens obtained at random during a planned dewatering of a 100‐m reach of the river, the sex ratio was biased toward females (proportion of females = 0.60). Morphometric analyses of 105 females and 108 males based on a generalized boosted classification model revealed elongated dorsal and anal fins in males correctly classified sex for 83% of individuals (95% CI = 77–88%). Seven independent observers used results from the generalized boosted classification model to assign sex to 30 fish, with average accuracy of 72% (range = 43–83%). The accuracy of the model and validation exercises were highest for fish >240 mm total length, the estimated length of reproductive maturity. Conclusion: Morphometrics based on dorsal‐ and anal‐fin sizes can be used to infer sex externally from hundreds of SACs removed per year to evaluate long‐term population management success. Impact statementSuckermouth armored catfish have invaded freshwater ecosystems globally, prompting increasing interest in control of nonnative populations. We provide a model for predicting sex of individuals based on external features as a means of advancing existing or future control programs. [ABSTRACT FROM AUTHOR]

Objective: Proliferative gill disease (PGD) in Channel Catfish Ictalurus punctatus and hybrid catfish (Channel Catfish × Blue Catfish I. furcatus) is attributed to the myxozoan Henneguya ictaluri. Despite evidence of decreased H. ictaluri transmission and impaired parasite development in hybrid catfish, PGD still occurs in hybrid production systems. Previous metagenomic assessments of clinical PGD cases revealed numerous myxozoans within affected gill tissues in addition to H. ictaluri. The objective of this study was to investigate the development and pathologic contributions of H. ictaluri and other myxozoans in naturally and experimentally induced PGD. Methods: Henneguya species‐specific in situ hybridization (ISH) assays were developed using RNAscope technology. Natural infections were sourced from diagnostic case submissions in 2019. Experimental challenges involved Channel Catfish and hybrid catfish exposed to pond water from an active PGD outbreak, and the fish were sampled at 1, 7, 10, 12, 14, 16, 18, and 20 weeks postchallenge. Result: Nine unique ISH probes were designed, targeting a diagnostic variable region of the 18S ribosomal RNA gene of select myxozoan taxa identified in clinical PGD cases. Partial validation from pure H. ictaluri, H. adiposa, H. postexilis, and H. exilis infections illustrated species‐specific labeling and no cross‐reactivity between different myxozoan species or the catfish hosts. After experimental challenge, mature plasmodia of H. ictaluri and H. postexilis formed in Channel Catfish but were not observed in hybrids, suggesting impaired or delayed sporogenesis in the hybridized host. These investigations also confirmed the presence of mixed infections in clinical PGD cases. Conclusion: Although H. ictaluri appears to be the primary cause of PGD, presporogonic stages of other myxozoans were also present, which may contribute to disease pathology and exacerbate respiratory compromise by further altering normal gill morphology. This work provides molecular confirmation and more resolute developmental timelines of H. ictaluri and H. postexilis in Channel Catfish and supports previous research indicating impaired or precluded H. ictaluri sporogony in hybrid catfish. Impact statementThis work implicates Henneguya ictaluri as the primary cause of proliferative gill disease, a devastating parasitic disease of U.S. catfish aquaculture, but demonstrates other myxozoan parasites can contribute to disease severity. The study better defines the developmental timeline of H. ictaluri and H. postexilis in Channel Catfish and supports research indicating impaired maturation of H. ictaluri in hybrid catfish. [ABSTRACT FROM AUTHOR]

Objective: Myxosporidiosis of bagrid fishes has been a focus of aquaculture research in recent years. The purpose of this study is to characterize a novel myxobolid, named Myxobolus xiushanensis n. sp., infecting Yellowhead Catfish Tachysurus fulvidraco in China. Methods: We used molecular biology, morphology, phylogeny, and histopathology in the present study. Result: Mature myxospores were circular to ellipsoidal in valve view, measuring 12.2 ± 0.4 μm (mean ± SD; range = 11.2–13.2 μm) in length and 10.6 ± 0.4 μm (9.5–11.1 μm) in width. Two oval polar capsules were equal in width (3.4 ± 0.2 μm; 3.0–3.8 μm) but slightly unequal in length: 5.6 ± 0.3 μm (5.3–6.1 μm) and 4.7 ± 0.2 μm (4.4–5.5 μm). The polar capsule was packed with five to seven spirals of polar tubules. Histopathological investigation demonstrated that the plasmodium under the cuticular layer of the gill arch only induced a local inflammatory response and did not cause serious damage to the gill arch's internal structure. The two small subunit (SSU) ribosomal DNA sequences of M. xiushanensis n. sp. showed 100% similarity and uniqueness, and the highest similarity with other myxosporean sequences in GenBank was 90.27% (query coverage = 94%). The secondary structures of the SSU ribosomal RNA revealed that the present species was distinctly different from related species in regions V4 and V7. Phylogenetic analysis showed that M. xiushanensis n. sp. clustered independently within a branch. Conclusion: These results enrich our understanding of the biodiversity of myxobolids infecting bagrid fishes and provide fundamental data for the diagnosis of myxosporidiosis. Impact statementThis study described Myxobolus xiushanensis n. sp. infecting the gill arch of Yellowhead Catfish Tachysurus fulvidraco in China. The results enrich our understanding of the biodiversity of myxobolids and provide fundamental data for the diagnosis of myxosporidiosis. [ABSTRACT FROM AUTHOR]

Aims: The aquaculture industry has been identified as one of the sources for the emergence of antimicrobial resistant bacteria. This study aimed to determine the level of bacterial contamination from selected catfish pond farming at Jasin, Melaka and its susceptibility to antimicrobial agents. The correlation between the sampling points' Water Quality Index and the level of bacterial contamination was also determined. Methodology and results: Sampling was carried out at six sampling points of the river as well as selected catfish pond farming. Microbial counts were assessed using the membrane filtration and isolates were further identified by using the polymerase chain reaction (PCR) method. Antimicrobial susceptibility tests were carried out using the disk diffusion method. Results showed that the total bacterial count obtained was not significantly different (P>0.05) between sampling points with an average of 4.47 ± 0.41 log CFU/mL. A total of 27 different bacterial species were identified where 63% were identified as Gram-negative bacteria. A medium negative correlation (r=-6.16, P<0.01) was found between the sampling points' Water Quality Index and the level of bacterial contamination. Among bacterial species identified, 18 species are pathogenic strains. Conclusion, significance and impact of study: Antibiotic susceptibility test indicated that only 4 isolates showed resistance to antimicrobials tested and the study shows the potential cross contamination between fishponds and Kesang River, Melaka. Thus, public health concerns are tangible, and prevention of the cross contamination is crucial for the farm. [ABSTRACT FROM AUTHOR]

This study describes the parasite community of non-native brown bullhead, Ameiurus nebulosus (Actinopterygii: Ictaluridae), collected at three sites in the river Vistula Basin (Lake Svitiaz, Lake Pisochne, and Lake on Plastova) and one site in the river Diester Basin (Lake Stryiska), in Ukraine. Our data represent the first comprehensive study of parasite community in this fish species in Europe. Sixteen parasite taxa were found, including species co-introduced from North America and species acquired in the European range. Maximum parasite richness (13 spp.) was recorded in Lake Svitiaz situated in a Natural Protected Area, while lowest species richness (3 spp.) was observed at Lake on Plastova, an artificial pond in the city of Lviv. Three co-introduced monogenean species, Gyrodactylus nebulosus, Ligictaluridus pricei and Ligictaluridus monticellii, are recorded in Ukraine for the first time, widening the knowledge of the European distribution of these North American parasites. Metric features for hard parts of invasive and native monogeneans showed overlap in ligictalurid parasites, but slightly smaller metrics in Ukrainian G. nebulosus, possibly reflecting water temperature during fish sampling. Though prevalence and abundance of acquired parasites was relatively low, infection parameters for metacercariae of Diplostomum spp. were relatively high at Lake Svitiaz and the natural Lake Stryiska in Lviv. In two lakes in the Vistula basin, we found high prevalence and abundance of Anguillicola crassus, an Asian nematode infecting eels, possibly supporting the invasional meltdown hypothesis. Our study confirms both further spread of non-native parasites in Europe and use of non-native fish as competent hosts for local native and introduced parasites. [ABSTRACT FROM AUTHOR]

The drop in temperature during the winter months can lead to a decrease in growth, induce metabolic stress, and increase mortality incidences. The present study evaluated the potential of functional feed additives in mitigating the negative impacts of winter‐rearing conditions in striped catfish (Pangasianodon hypophthalmus). Four test diets were evaluated over a twelve‐week feed trial: (1) zinc‐acetate (Zn‐acetate), (2) selenomethionine (Se‐Met), (3) β‐glucan, and (4) control with no added feed additive. The survival rate in the β‐glucan (95.00%) and Zn‐acetate (93.30%) dietary groups was higher than the control (78.30%) and Se‐Met (85.00%). Fish fed with the β‐glucan had the highest weight gain (20.75% increase), specific growth rate (13.75% increase), and lower feed conversion ratio (9.64 % decrease). However, feed additives did not influence the fatty acid profiles or whole‐body proximate composition. Although, Zn‐acetate and Se‐Met had higher body ash content. Serum cortisol and glucose levels were lower in β‐glucan and Zn‐acetate than in other treatment groups. All feed additives resulted in higher superoxide dismutase, glutathione peroxidase, and catalase activity in the liver and muscle. This study found that β‐glucan and zinc‐acetate can improve cold stress resistance and offer a sustainable strategy for catfish rearing over winter. [ABSTRACT FROM AUTHOR]

Animal aggregation, particularly in large-bodied species, is both a fascinating and intriguing phenomenon. Here we analyzed the overwintering behavior of the European catfish, Silurus glanis Linnaeus, 1758, the largest freshwater fish in Europe. By tracking 47 subadults and adults in a shallow lake in southeastern France, we reported a consistent aggregative behavior across four successive winters. By implementing time series analysis and Cox proportional hazard models, we investigated the dynamics of these aggregations (formation, stability, dislocation), and the factors that govern it, whether external (temperature, time of the day) or specific to the fish (size, key individuals). These aggregations lasted 1.5–2 months and mainly took place in a single small 4 m-deep area whose environmental conditions (temperature, oxygen, substrate) did not differ from other parts of the lake. In some periods during winter, all tagged fish were aggregated, which suggests that a large proportion of the lake population gathered there. Low temperatures (below 9 °C) triggered the formation of aggregations. They became more stable with decreasing temperatures, while individuals more frequently left the aggregation, preferentially at dusk and at night, when temperatures increased. The largest individuals swam more frequently back and forth to the aggregation. Irrespective of their size, some individuals consistently arrived earlier in the aggregation in winter and left later. This predictable seasonal grouping of individuals and, more generally, the knowledge provided by such studies on how species use space have important operational value and are useful for species conservation as well as for species control. [ABSTRACT FROM AUTHOR]

Abstract A new species of Pimelodella is described from the rio Paraguai basin in Mato Grosso do Sul and Mato Grosso States, Brazil. The new species distinguishes from all other members of the genus based on a unique combination of characteristics, which include: dorsal profile straight from snout to dorsal-fin, maxillary barbel reaching at least the anal-fin terminus when parallel to main body axis, robust dorsal-fin spine bearing small spinules along three-fourths of its posterior margin, 41–42 total vertebrae (rarely 43 or 44), 13–23 large and retrorse blades at the posterior margin of the pectoral-fin spine, and dorsolateral region of body slightly darkened. This study also discusses the ichthyofaunal similarities between the Paraguai and Amazon basins, shedding light on their biogeographic history. Additionally, the research includes considerations about the sexual dimorphism of Pimelodella and provides an identification key for the Pimelodella species found in the Paraguai basin.

We report the first record of Platyclarias machadoi Poll, 1977 since its original description. This species was sampled by electrofishing in rapids on the Kwanza River upstream of Capanda Dam in Angola. Morphomet-ric and meristic data for the Kwanza River material were compared to published data from the Platyclarias type series. Osteology was compared between the Kwanza specimens and two Platyclarias paratypes using computed tomography (CT) scans. Prior to this discovery, the genus was known only from the Kwango River in Angola.

The Neotropical monophyletic catfish genus Harttia represents an excellent model to study karyotype and sex chromosome evolution in teleosts. Its species split into three phylogenetic clades distributed along the Brazilian territory and they differ widely in karyotype traits, including the presence of standard or multiple sex chromosome systems in some members. Here, we investigate the chromosomal rearrangements and associated synteny blocks involved in the origin of a multiple X1X2Y sex chromosome system present in three out of six sampled Amazonian-clade species. Using 5S and 18S ribosomal DNA fluorescence in situ hybridization and whole chromosome painting with probes corresponding to X1 and X2 chromosomes of X1X2Y system from H. punctata, we confirm previous assumptions that X1X2Y sex chromosome systems of H. punctata, H. duriventris and H. villasboas represent the same linkage groups which also form the putative XY sex chromosomes of H. rondoni. The shared homeology between X1X2Y sex chromosomes suggests they might have originated once in the common ancestor of these closely related species. A joint arrangement of mapped H. punctata X1 and X2 sex chromosomes in early diverging species of different Harttia clades suggests that the X1X2Y sex chromosome system may have formed through an X chromosome fission rather than previously proposed Y-autosome fusion. [ABSTRACT FROM AUTHOR]

Host–parasite dynamics involve coevolutionary arms races, which may lead to host specialization and ensuing diversification. Our general understanding of the evolution of host specialization in brood parasites is compromised by a restricted focus on bird and insect lineages. The cuckoo catfish (Synodontis multipunctatus) is an obligate parasite of parental care of mouthbrooding cichlids in Lake Tanganyika. Given the ecological and taxonomic diversity of mouthbrooding cichlids in the lake, we hypothesized the existence of sympatric host‐specific lineages in the cuckoo catfish. In a sample of 779 broods from 20 cichlid species, we found four species parasitized by cuckoo catfish (with prevalence of parasitism of 2%–18%). All parasitized cichlids were from the tribe Tropheini, maternal mouthbrooders that spawn over a substrate (rather than in open water). Phylogenetic analysis based on genomic (ddRAD sequencing) and mitochondrial (Dloop) data from cuckoo catfish embryos showed an absence of host‐specific lineages. This was corroborated by analyses of genetic structure and co‐ancestry matrix. Within host species, parasitism was not associated with any individual characteristic we recorded (parent size, water depth), but was costly as parasitized parents carried smaller clutches of their own offspring. We conclude that the cuckoo catfish is an intermediate generalist and discuss costs, benefits and constraints of host specialization in this species and brood parasites in general. [ABSTRACT FROM AUTHOR]

The largefin longbarbel catfish, Hemibagrus macropterus, is an economically important fish species in southwestern China, with males growing faster than females. This study presents a high-quality chromosome-level genome assembly of the largefin longbarbel catfish, generated by integrating Illumina short reads, PacBio HiFi long reads, and Hi-C data. The assembled genome size was 858.5 Mb, with a contig and scaffold N50 of 5.8 Mb and 28.4 Mb, respectively. A total of 656 contigs were successfully anchored to 30 pseudochromosomes with a BUSCO score of 97.7%, consistent with the number of chromosomes analyzed by karyotype. The genome contained 29.5% repeat sequences, and a predicted total of 26,613 protein-coding genes, of which 25,769 (96.8%) were functionally annotated in different databases. Evolutionary analysis showed that H. macropterus was most closely related to H. wyckioides, with a divergence time of approximately 16.3 million years. Chromosomal syntenic relationships among H. macropterus, H. wyckioides, and Pelteobagrus fulvidraco revealed a one-toone relationship for most chromosomes, except for break, fission, and inversion of some chromosomes. The first high-quality reference genome will not only provide a valuable genetic resource for the study of sex determination mechanisms and genetic breeding of largefin longbarbel catfish, but also contribute to comparative analyses of genome and chromosome evolution within Siluriformes. [ABSTRACT FROM AUTHOR]

Our study helps to evaluate the immune response, antioxidative status, and resistance against heat stress (HS) in Clarias gariepinus treated with propolis extraction; the results will contribute to theories of fish physiology and immunity under high-temperature conditions. Forty-five fish were divided into three equal groups: the control, the HS group at 36 °C, and the HS treated with alcoholic extraction of propolis that dissolved in water for 3 weeks. The results of our study suggested that the stress response differs among tissues thymus, spleen, and liver. All the tissues showed alteration in morphological and cytological structure at the light microscope (LM) and transmission electron microscope (TEM); thymus showed edema and thymocyte destruction; the spleen detected collagen deposition, and the liver displayed endoplasmic reticulum amplification (ER). In addition, we examined oxidative stress and antioxidant defenses (lipid peroxidation, catalase, and glutathione) of the spleen and measured blood biochemical parameters (alanine transaminase and aspartic transaminase levels) after heat stress. However, this toxic effect of HS was neutralized by the propolis extraction. To conclude, propolis is recommended to cope with the impacts of heat stress on catfish (Clarias gariepinus) by improving immunity and antioxidative resistance. [ABSTRACT FROM AUTHOR]

The cloning and characterization of the complete coding sequence of the Clarias magur SRD5A1 (CmSRD5A1) gene, which encodes an enzyme responsible for regulating steroid levels by converting testosterone into 5α-dihydrotestosterone (DHT), have been successfully achieved. DHT plays a vital role in enabling the complete expression of testosterone's actions in neuroendocrine tissues. The ORF of the full-length cDNA sequence of SRD5A1 was 795 bp, translating into 265 amino acids, with a total length of 836 bp including UTRs. Like other vertebrates, the signal peptide analysis revealed that SRD5A1 is a non-secretory protein, and hydropathy profiles indicated that it is hydrophobic in nature. The 3D structure of CmSRD5A1 sequence generated above was predicted using highly accurate AlphaFold 2 in Google Colab online platform. CmSRD5A1 contains seven transmembrane helices connected by six loops, with the N-termini located on the periplasmic side and C-termini on the cytosolic side. Structural superimposition with known bacterial and human SRD5As showed very high structural similarity. The electrostatic potential calculation and surface analysis of CmSRD5A1 revealed the presence of a large cavity with two openings one highly electropositive towards the cytosolic side and another relatively neutral towards the transmembrane region. The structural comparison revealed that the electropositive side of the cavity should bind to NADPH and the steroid hormone in the hydrophobic environment. Polar residues binding to NADPH are highly conserved and the same as known strictures. The conserved residues involved in hydrogen bonding with the ketone group at C-3 in the steroids hence fevering Δ4 double-bond reduction are identified as E66 and Y101. Our findings showed that SRD5A1 expression was lower during the spawning phase than the preparatory phase in female fish, while the administration of Ovatide (a GnRH analogue) resulted in up-regulation of expression after 6 h of injection in the ovary. In males, the lowest expression was observed during the preparatory phase and peaked at 16 h post- Ovatide injection in the testis. The expression of SRD5A1 in the brain of female fish was slightly higher during the Ovatide stimulation phase than the spawning phase. This study represents the first report on the cloning and characterization of the full-length cDNA of SRD5A1 in Indian catfish. [ABSTRACT FROM AUTHOR]

A better understanding of trophic interactions between hardhead catfish (Ariopsis felis) and gafftopsail catfish (Bagre marinus) is crucial for developing multi-species management strategies for the northern Gulf of Mexico (GOM). These two species are often aggregated in food web models; however, limited data are available to substantiate this approach. Therefore, the present study aimed to describe the dietary habits of hardhead catfish and gafftopsail catfish using analysis of stomach contents aided by DNA barcoding. Hardhead (n = 693) and gafftopsail (n = 655) catfish were sampled in the northern GOM from 2015–2019 using both fisheries-dependent and -independent techniques. The average percent number (%N), average percent mass (%M), prey specific number (%PN), prey specific mass (%PM), and prey-specific index of relative importance (%PSIRI) were computed to quantify prey species. The stomach content analysis identified distinct differences in diet between hardhead and gafftopsail catfish. Crustaceans were the most important prey for hardhead catfish, while gafftopsail catfish showed a significantly broader dietary breadth and were primarily piscivorous. Multivariate analyses indicated that the location of capture explained the greatest amount of diet variability for both species. These findings address fundamental knowledge gaps regarding the dietary habits of hardhead and gafftopsail catfish in northern GOM ecosystems. [ABSTRACT FROM AUTHOR]

A new rheophilic species of the genus Rineloricaria is described for the Amazon basin in Colombia. Rineloricaria cachivera n. sp. differs from its congeners by having anterior to the first predorsal plate, an inconspicuous saddle‐like mark; the presence of dark, diffuse blotches, present as unified dark colouration along most of the dorsal portion of the head, without bands or spots on the head; a long snout that occupies more than half the head length (HL), between 58.0% and 66.3% HL; a naked portion on the cleithral area from the border of lower lip reaching the origin of pectoral fin; and by having five series of lateral plates in longitudinal rows below the dorsal fin. The new species is morphologically similar to Rineloricaria daraha; however, it can be distinguished by the presence of six branched pectoral fin rays (vs. seven) and the lower lip surface with short thick papillae (vs. long finger papillae). An identification key to the Rineloricaria species of the Amazon River basin in Colombia is provided. The new species is herein categorized as Least Concern, following the IUCN criteria. [ABSTRACT FROM AUTHOR]

The European catfish Silurus glanis is attracting growing interest as an object of fisheries and aquaculture, which is reinforced by the expansion of its natural range under climate change. Shaping the effective exploitation strategy for this valuable species requires detailed knowledge of its biology, including feeding and digestion processes, especially near the natural limits of the species range. Meanwhile, the digestion physiology of the European catfish remains poorly explored, including the activity of major digestive enzymes and the possible effect of intestinal parasites on this activity. In this regard, the activity of proteinases and α‐amylase in the intestinal mucosa of the catfish was studied. Adult catfish were collected in the Rybinsk reservoir (Upper Volga) located close to the northern limit of the species range. It was shown that all subclasses of intestinal digestive proteinases, including serine proteinases, metalloproteases and cysteine (thiol) proteinases, function in the gut mucosa of the catfish. The mucosal levels of total proteolytic activity depended on fish size, in contrast to those of trypsin, chymotrypsin and α‐amylase. The level of chymotrypsin activity was significantly higher than that of trypsin activity. It was also found that the incubation medium and extract of the cestodes Silurotaenia siluri parasitizing the catfish gut had a significant inhibitory effect on the activity of serine proteases (trypsin and chymotrypsin) operating in the intestines of the host fish. [ABSTRACT FROM AUTHOR]

An iterative analysis of Imparfinis, combining phylogenetic analysis based on cytochrome oxidase gene and multivariate morphometrics, revealed a new cryptic species from the Andean tributaries of the Orinoco River basin, which is described here. The new species is sister to a clade constituted by Imparfinis hasemani and Imparfinis pijpersi, both from the river basins of the Guiana Shield, being also the most geographically proximate species. Nonetheless, the new species is most similar in general appearance to Imparfinis guttatus from the Madeira and Paraguay River drainages, being almost undistinguishable by conventional characters of external morphology, differing only by morphometric attributes overall. The new species can be distinguished from the remaining congeners by a unique combination of characters, including lower lobe of caudal fin darker than upper lobe, maxillary barbel reaching or surpassing pelvic‐fin insertion, 12–15 gill rakers on first gill arch, 40–42 total vertebrae and 9–10 ribs. The new species constitutes the only representative from the Orinoco River basin belonging to Imparfinis sensu stricto. [ABSTRACT FROM AUTHOR]

Aspidoras fuscoguttatus Nijssen & Isbrücker, 1976 is a small, relatively common armored catfish considered endemic to the upper Paraná river basin. Here, based on recent collections, as well as morphological and molecular evidence, the known geographic distribution of this species is extended to the basin of the São Francisco River. Specimens were collected during biological surveys in two unnamed tributaries of the Paraopeba River, in the headwaters of the São Francisco River. The new records may be a consequence of headwater stream-captures between São Francisco and upper Paraná drainages. Continued surveys are needed to assess and mitigate natural and human impacts, including biological exchanges between basins. [ABSTRACT FROM AUTHOR]

Aquaponics with bio-floc can potentially offer sustainable food production with zero waste as it allows farming plants and fish simultaneously, whereby the former use fish waste as their nutrient sources, while the latter receives cleaner water from the plants in a closedloop system. In the aquaponics system, additional nutrients are usually added to support optimal plant growth, but it is suggested that the amount of such chemical nutrients should be controlled to prevent any harm to the fish. Furthermore, the plant and fish growth rates are influenced by the nutrients and the culture media used. This study aims to examine the effect of nutrition (full-nutrient and half-nutrient treatments) and different types of culture mediums (rockwool, rockwool-perlite, and rockwool-husk) on the growth rates of pak choi (Brassica rapa) and catfish (Clarias gariepinus) using split-plot design. Findings show that the half-nutrient treatment yielded a 17.12% higher plant growth rate and 23.87% heavier catfish weight than the full-nutrient treatment, but these treatments did not affect the fish survival rate. It was also observed that using different culture mediums did not result in any significant difference. [ABSTRACT FROM AUTHOR]

The current study aimed to assess the population status of Schilbe mystus in stratum VII of Volta Lake, Ghana, based on length-frequency data collected throughout 2021. Individual fish samples, ranging from 5.5 to 22.0cm with a mean length of 11.5± 0.17cm, were analyzed using FiSAT II. The study revealed a mean condition factor of 0.36, indicating the fish's overall health. The growth pattern, estimated at 3.1 suggested positive algometric growth. The growth rate (K) was determined as 0.25 per year. Length at infinity (L8), length at first capture (Lc50), and length at first maturity (Lm50) were calculated as 24.7, 10.27, and 16.47cm, respectively. The growth performance index was recorded at 2.58. The total mortality rate (Z) was calculated as 2.09 per year, with the natural mortality rate (M) at 0.78 per year and the fishing mortality rate (F) at 1.31 per year. The exploitation rate was 0.63, indicating overexploitation of S. mystus in Stratum VII. To sustain the stock size of the S. mystus fishery in Lake Volta, we recommend reducing fishing efforts, regular status assessments, and enforcement of fisheries regulations. [ABSTRACT FROM AUTHOR]

We integrated large sample sizes, morphometric and molecular data, and phylogenetic and species delimitation analyses to test the 17-year-old hypothesis that only two species of whisker-cheeked suckermouth catfishes (genus Lasiancistrus) occur in river drainages west of the Andes Mountains. Our results reject this hypothesis, demonstrating that, in addition to the previously recognized Lasiancistrus guacharote from Lake Maracaibo, a Lasiancistrus clade from west of the Sierra de Perijá contains at least four allopatric, genetically differentiated and morphologically distinct lineages. One of these lineages had no previous name associated with it and is described here as the new species Lasiancistrus wiwa. Phylogenetic relationships and geographical distributions of all five trans-Andean lineages are concordant with watershed boundaries and major mountain ranges that form these boundaries, with the following five freshwater basins or regions each containing a single species: Lake Maracaibo (L. guacharote), Rancheria River basin (L. wiwa), Upper and Middle Magdalena River and lower Cauca River basins (Lasiancistrus volcanensis), Upper Cauca River basin (Lasiancistrus caucanus) and Pacific Coastal watersheds between central Colombia and central Panama (Lasiancistrus mayoloi). Evolutionary relationships among these lineages suggest that Andean uplift-mediated vicariance contributed significantly to the cladogenesis and allopatric distributions of these fishes. [ABSTRACT FROM AUTHOR]