Journal of Applied Ichthyology最新文献

The rainbow trout, Oncorhynchus mykiss, is the most extensively cultured coldwater fish species in India. However, skeletal deformities remain a significant concern and are frequently reported in rainbow trout farming operations. The incidence of skeletal deformities can serve as an indicator of the quality of rearing conditions and environmental factors. The present study was conducted to assess the skeletal deformities of rainbow trout, from selected farms in Himachal Pradesh, and Uttarakhand, India. During the study, physicochemical parameters such as water temperature, pH, dissolved oxygen (DO), nitrogen and phosphorus compounds, and chlorides were recorded. The brain, gill, and muscle tissues were examined under optical microscope to inspect myxozoan parasite infections. Nevertheless, myxozoan parasites were not detected in the microscopic examination. For histopathological analysis, tissue samples from the internal organs were processed. The degree of acinar cell necrosis, fibrosis, and macrophage aggregation were determined through histopathological examination. The skeletal deformities, whirling behavior, and mortality were directly associated with the major pancreatic anomalies but no signs of parasite presence.

Identification of polymorphism in growth-related genes and their association with growth traits is an area of intense research. The growth rate is the most sought-after economic trait in the breeding program of fish. The significant association of polymorphism will aid in marker-assisted selection and speed up the genetic improvement program. The present study was performed in a population of common carp belonging to an ongoing selective breeding program at ICAR-CIFE, Rohtak Center. A total of 50 common carp based on the breeding value for body weight were selected and bifurcated into two groups: high and low performers. Each fish had three records (based on pond age) for growth-related traits, viz., body weight (Bw), body length (Bl), and body height (Bh). At 200 days of pond age, the mean Bw, Bl, and Bh for high performers was 494.28 ± 52.12 g, 23.764 ± 0.63 cm, and 9.36 ± 0.35 cm, respectively, whereas the mean Bw, Bl, and Bh for low performers was found to be 165.72 ± 17.31 g, 16.20 ± 0.57 cm, and 6.40 ± 0.23 cm, respectively. The DNA was extracted from the fin clips of these fish. Five primers were used to amplify five distinct regions of the growth hormone gene covering five exons and four introns. The positive PCR products were purified and subjected to Sanger sequencing. The sequences with a Phred quality score above 20 were imported in Sequencher V for SNP hunting. Five polymorphic sites were detected, viz., C165 (amplicon 3), D60 (amplicon 4), D114 (amplicon 4), E90 (amplicon 5), and E185 loci (amplicon 5). The population genetic analysis was performed using GenAlex V. The D60 and E185 loci significantly deviated from the Hardy–Weinberg equilibrium (p < 0.05). Growth association was performed for the polymorphic loci using a linear model by invoking PROC GLM in SAS. The loci C165, D60, and E90 were significantly associated with the Bw, Bl, and Bh. The results obtained in this study must be utilized in the ongoing selective breeding of common carp to speed up genetic improvement.

To reconstruct the life history of Coilia nasus in the Shandong section of the Yellow River, an electron probe microanalyzer (EPMA) was employed to analyze the Sr and Ca values in the otoliths of 12 individuals collected from Pangkou Bay. The results indicated that the life history of C. nasus is complex and diverse, the individuals in this study can be categorized into five distinct patterns. Pattern I includes P1, P2, P3, and P4, whose life history tracks indicate hatching in brackish water near the Yellow River estuary; after approximately 1 year, they begin to migrate along the Yellow River to Pangkou Bay for spawning. Pattern II encompasses P9, P12, and P13, which hatch in freshwater habitats; as these individuals grow, there is an abrupt change from Stage 1 to Stage 2, but their life history does not extend to marine habitats with high Sr/Ca values, and after about 1 year, they migrate along the Yellow River to Pangkou Bay for spawning. Pattern III includes P6, P8 and P10, which also hatch in freshwater habitats and experience abrupt changes; however, the mapping analysis reveals a large area of red and yellow concentric rings, indicating a history of seawater habitat and an extension of their life history to Laizhou Bay. Pattern IV is represented by P11, whose living environment was relatively stable, with no significant abrupt changes and no migratory life history characteristic, which presumed to be a freshwater settlement type that passively entered the Yellow River due to the flood season of Dongping Lake. Pattern V is exemplified by P7, whose analysis results show two trips to freshwater and brackish water habitats, both of which produced significant pattern changes which indicates that it conducted a reproductive migration at the first instar, swam to the Yellow River estuary after spawning, and migrated to Pangkou during the reproductive period of the following year to lay eggs until it was captured. This study demonstrates that most individuals in Pangkou Bay are of the migratory type. Compared with the sexual maturity of individuals in other waters of the Yangtze River basin, Pangkou Bay is identified as an important spawning ground for the migratory type of C. nasus.

Global climate change significantly influences environmental temperature, affecting the feeding patterns, growth, and overall health of fish. Understanding how fish respond to thermal changes is crucial, particularly for growth and stress response in aquaculture. This study examines the effects of different acclimation temperatures on the expression of stress, appetite, and growth-related genes in Nile tilapia (Oreochromis niloticus). Quantitative real-time PCR method was employed to analyze the expression of genes for growth hormone (gh) from the pituitary, insulin-like growth factors (igf1 and igf2), ghrelin, and heat shock proteins (hsp70 and hsp90) from the liver of juvenile Nile tilapia acclimated to 31°C (control), 34°C, and 37°C for 14 days. Results revealed that the expression of hsp70 and hsp90 as well as the level of blood glucose were significantly upregulated at 37°C in both males and females, indicating a pronounced stress response due to higher acclimation temperature. Conversely, the expressions of gh, igf1, and igf2 were highest at 34°C, stimulating metabolic processes and promoting somatic growth. In comparison, significantly lower expression of these genes was observed at 37°C, suggesting an inhibitory effect of higher temperatures on growth processes. Expression of ghrelin followed a similar pattern to that of GH and IGFs with higher levels at 34°C correlating with increased appetite and growth, but a decreased expression at 37°C, indicating reduced feeding activity resulting from thermal stress. These findings underscore the critical role of maintaining optimal temperatures in aquaculture settings and provide valuable insights into the physiological mechanisms underlying thermal adaptation in Nile tilapia under varying environmental conditions.

The current study was conducted at the Bangladesh Fisheries Research Institute in Cox’s Bazar, from February 2023 to April 2024. Oyster (Crassostrea virginica) growth and survival rate were studied in a recirculating aquaculture system (RAS). The study also evaluated the impact of various water parameters (viz., temperature, pH, dissolved oxygen [DO], salinity, alkalinity, nitrite, nitrate, and ammonia) on oyster development. Oysters were cultivated in T1, T2, and T3 using two replications for each treatment. RAS was used with continuous aeration throughout the two treatments (T1 and T2), while non-RAS continuous aeration was given during the control treatment (T3). 50, 60, and 55 oysters were presented in three treatments. Three distinct marine microalgae (Nannochlorum spp., Tetraselmis spp., and Nannochloropsis spp.) were added to tanks for feeding oysters. Statistically significant differences (p < 0.05) were found in the T1 therapy group, which had the highest specific growth rate per day (0.119%) and survival rate (92.85%), followed by T2 (87.5%) and T3 (77.5%). In addition, first treatment (T1) continuously measured the largest weight (36.08 g), length (6.51 cm), and width (6.43 cm); however, T2 showed a significant depth rate (4.44 cm). Optimum oyster population, salinity (29.5 ppt), pH (7.25), DO (5.12), temperature (30.75°C), and other water quality indicator levels displayed a significant correlation with oyster growth performance for the T1 group rather than T2 and T3. However, the T2 group was also treated under RAS circumstances. The findings demonstrated that RAS can significantly enhance oyster growth and survival-controlling water indicators, which provide valuable insights for sustainable aquaculture practices in the coastal areas of Bangladesh.

Growth rates are generally obtained from back-calculation of increments of otolith readings and based on the assumption that mean annual growth can be scaled directly to the distance between age rings. Although otoliths continue to grow even when somatic growth ceased. To analyse growth rates of yellow eel, a passive integrated transponder (PIT) mark-recapture study was performed in four water bodies (Delfland, Markiezaatsmeer, Süderpolder and Vinkeveense Plassen) in the Netherlands. PIT-tags were used as an alternative method instead of the generally applied back-calculation of annual increments from otolith readings. During 2017–2020, 2209 eels were tagged individually and in the subsequent years, 541 eels were recaptured. The mean annual growth rate decreased with increasing length of eel, with growth rates of 2.2–8.8 cm/year for undifferentiated (sex undetermined) eel between 30 and 50 cm and 1.3 and 5.7 cm/year for female eel between 50 and 80 cm. Differences in growth rate were also observed between the four water bodies, which having consequences to population demographics, such as age at first maturity.

Water pollution resulting from petroleum derivatives, notably diesel fuel oil, has emerged as a significant environmental concern recently. The experiment was conducted to find out the impact of diesel oil on morphology, behavior, and changes in internal organs i.e., heart, intestine, kidney, and liver in Nile tilapia (Oreochromis niloticus). There were controls and three groups of Nile tilapia (Oreochromis niloticus) exposed to 0 mL/L (control), 0.5 mL/L, 1.0 mL/L, and 1.5 mL/L of diesel for 15 days. Several morphological changes such as a broken fin, rough scale, increased mucous, and discolored gill were recorded. The treated fish displayed erratic swimming patterns, rapid operculum movements, and hovering in the water column, displaying signs of weakness whereas the untreated (control) remained calm and normal. Probit analysis revealed that the mortality rates were increased significantly (p < 0.05) with the increase of diesel concentrations. Multiple histopathological abnormalities were found and they were fragmentation of myocardial muscle fiber and formation of degenerative vacuoles in the heart; degeneration of epithelium, submucosa, and hemorrhage in the mucosa of the intestine; hemorrhages of glomerulus and dilation of tissues in the kidney; and enlargement of central vein, degeneration of hepatocyte, dilation of the sinusoid, hemorrhage, vacuolization of hepatocytes, necrosis, and thickening of the hepatocytic cells in the liver. This study also concluded that the dissolved oxygen levels decreased with the increase of oil concentrations, which led to poor water quality and had a significant effect on morphology, behavior, histology, and mortality. This study will grow social awareness and people will handle commercial diesel oil properly during transportation. Thus, the present findings might be helpful to save aquatic animals as well as aquatic environments.

Climate change is causing saline intrusion, negatively affecting aquaculture productivity on a global scale. It is necessary to explore suitable species for coastal aquaculture in water with low to moderate salinity. Thus, the objective of the present study was to assess the impact of salinity on the growth performance, muscle composition, and blood parameters of a farmed fish, Gangetic mystus (Mystus cavasius). For this experiment, the fingerlings were raised in the aquarium for 60 days. Three distinct salinities, specifically 3, 6, and 9 parts per thousand (ppt), were employed for treatment 2 (T2), treatment 3 (T3), and treatment 4 (T4), whereas treatment 1 (T1) was referred to as the control with a salinity of 0 ppt. Increasing salinity did not have any influence on the water quality parameters. The survival rates were 97.5 ± 0%, 96.25 ± 1.25%, 92.5 ± 2.5%, and 90 ± 5% for T1, T2, T3, and T4, respectively. The highest specific growth rate (SGR) and the percentage of weight gain (PWG) and the lowest food conversion ratio (FCR) were recorded at T1. T2 and T3 showed descending values for SGR and PWG and ascending values for FCR. Moreover, the body protein percentage reduced by about 2%, and lipids increased by 13% in T3 compared to T1. RBC and Hb exhibited an inverse relation with increasing salinity, whereas WBC and glucose displayed an opposite trend due to stressed conditions. Thus, the study implies that while salinity does hinder growth performance and compromise the immune system to some degree, M. cavasius is capable of enduring salinity levels of up to 6 ppt while maintaining a satisfactory survival rate.

Bosten Lake is an important inland freshwater lake in China, which is rich in fishery resources. However, due to various factors, its fishery resources have declined. The length–weight relationship (LWR) is of great significance for fish research and fishery management. This study was based on the samples of 17 freshwater fish species collected from 10 sampling points in Bosten Lake from March 2023 to November 2024. The LWRs were determined, the regression parameters and the coefficient of determination (R²) were calculated, and the fish condition factor BW/TL³ was analyzed. The results showed that the b value of the LWR parameters of the 17 freshwater fish species ranged from 1.262 to 3.665. The b values of most fish species were within the expected range. The LWRs of all fish species were significantly different (p < 0.05), and the R² values ranged from 0.746 to 0.999. The LWR of Aristichthys nobilis was the strongest, and that of Rhodeus ocellatus was the weakest. This study reported for the first time the LWRs of Channa argus in the lake, and its b value was the highest, and the growth pattern was related to its ecological niche. The research results provide basic data and theoretical basis for fish ecology research, fishery resource management, and lake ecological protection.

Artificial expansion of shipping routes in the course of international trade opens up fish migration routes for numerous species. Since 2006 migration of four different goby species took place from the Ponto–Caspian region to the Lower Rhine. Neogobius fluviatilis, Neogobius melanostomus, Proterorhinus semilunaris and Ponticola kessleri were able to establish in the local fish community of the Lower Rhine. Besides the four other goby species, Knipowitschia caucasica migrated from the Ponto–Caspian region to the Lower Rhine as well in 2019. Due to increasing abundance in the last years and lack of information regarding population dynamics, feeding activity and prey preferences of the dwarf goby, the length of 1218 Caucasian dwarf gobies was analysed as well as the diet of 519 individuals in the course of May 2021 to February 2022. The populations of three different locations along the Lower Rhine were examined in winter on differences in population dynamics and feeding ecology. Analysis of the population over time suggests that K. caucasica in the Lower Rhine is an annual species with spawning during summer. The juvenile individuals of the Caucasian dwarf goby increased in total length until winter, while the adults vanished after spawning. Both juveniles and adults mainly fed on zooplankton and insect larvae. The feeding activity of the dwarf goby was higher in summer than in winter and started to increase as early as February. No difference in winter prey was recorded between populations at different sites, as all populations fed mostly on copepods and chironomids.