Iranian Journal of Fisheries Sciences
Volume:20 Issue: 6, Nov 2021

The incidence of Lactococcosis caused by Lactococcus garvieae, in rainbow trout (Oncorhynchus mykiss, Walbaum, 1792) farms is disquieting and increasing in recent years. Knowledge of biotypes and serotypes involved in disease incidence is essential to adopt disease prevention and control policies. Twelve isolates of L. garvieae from some rainbow trout farms were identified by phenotypic, biochemical, and molecular assays. Biotyping of the isolates was undertaken based on the acidification of carbohydrates including sucrose, tagatose, mannitol, and cyclodextrin as well as the presence of pyroglutamic acid arylamidase (Pyra) and N-acetyl-β-glucosaminidase (β-Nag) enzymes. The Serotyping classification was carried out using slide agglutination assay. The obtained results showed that all isolates were identified as biotype II. Seven isolates (58.3%) were positive for capsule formation and were classified as KG- strain and 41.7 % were classified as KG+ strains (non-capsulated strains). Further works are required for a better understanding of the diversity of Lactococcus garvieae isolates in farmed rainbow trout in Iran.

Length-Based Spawning Potential Ratio (LB-SPR) model was applied to describe the status of Javelin grunter, Pomadasys kaakan in the Persian Gulf and Oman Sea. From April 2002 to March 2019. 45,489 specimens were collected from fish landing sites monthly, and their length (FL) and weight were measured. The results of the present study showed that different gears captured most of the P. kaakan before first spawning time. The maximum-recorded length for this species in the study area was 60 cm FL with a mean length of 43.0±4.73 cm. The M/K value corresponds to P. kaakan maturation was calculated as 0.53. Based on the LB-SPR assessment model, it could be concluded that these species become vulnerable to fishing at its maturation’ size (48 cm). The range of annual SPR of P. kaakan was estimated between 0.14 to 0.18 in the Persian Gulf and Oman Sea (Iranian waters), which is even lower than the threshold value of 0.2. Such results suggest that the exploitation of P. kaakan occurred above the maximum sustainable limit and has a confounding effect on successful recruitment and juvenile survival of this species. The Spawning Potential Ratio of P. kaakan based on time series analysis, as a biological reference point was estimated below 0.2, which means for achieving a higher SPR level and sustainable fisheries, the rate of fishing mortality should be reduced constantly.

The aim of this study was to investigate the effect of red pepper (Capsicum annuum) extract on growth, blood, biochemical and non-specific immune parameters of 360 rainbow trout (Oncorhynchus mykiss) juveniles with average weight of 9.38±0.01 g. The fish were fed with a commercial diet containing 0, 0.25, 0.5 and 1% of C. annuum extract in 12 tanks (300L) with three replicates (30 fish per tank) for 30 days. Then, Yersinia ruckeri was injected by intraperitoneal to evaluate fish resistance. At the end of fish feeding period, growth and survival, as well as blood and immune parameters were assessed. The highest level of weight gain (%) and SGR and also the least level of FCR were observed in fishes fed by 0.5% red pepper extract (p<0.05). Hematological parameters (RBC, WBC and hemoglobin) significantly increased in fish fed with 0.25 and 0.5% of C. annuum extract for 30 days and after challenging with Y. ruckeri as compared to the control group. Lysozyme and complement contents indicated significant increases in all treatments fed with red pepper extract after bacterial infection (p<0.05). Generally, it can be concluded that rainbow trout fed with 0.5 % red pepper extract for a month could gain more weight and enhance immune responses against infectious diseases.

The aim of this study was to determine the effects of cobalt concentration on cell growth, some biochemical composition, and fatty acids profile of the marine microalga Tetraselmis subcordiformis. Cobalt deprivations did not cause a considerable change in growth photosynthesis activity as compared to the control group. Induction of maximum lipid production was achieved using 0.001 mg L-1 of cobalt-deprived T. subcordiformis. The highest crude protein content (33.75 mg L-1) was observed in 0.001 mg L-1 cobalt. The highest and lowest lipid accumulation in T. subcordiformis was observed in 0.001 mg L-1 and 10 mg L-1 cobalt, respectively. Under cobalt deficient conditions, T. subcordiformis produced a large quantity of saturated fatty acids and iodine and saponification value. Biodiesel characteristics were enhanced with Co+2 reduction. Also, biodiesel quality decreased with increase of cobalt. The results showed that the maximum and minimum carotenoids were observed in 0.1 and 10 mg L-1 cobalt, respectively.

There is an on-growing demand for alternative sources of commercial gelatin. The by-products generated by fish-processing industries are a potential source for the production of halal gelatin in different industries such as food products. In this study, pastille was formulated with different concentrations of fish (Benthosema pterotum) (FG) and bovine (BG) gelatins. Different quality attributes of gelatin including humidity, ash, protein, water activity, sensory, texture and color were investigated. Statistical analysis was done by the ANOVA and LSD test was applied for mean comparison of the samples at p<0.05. Data analysis was carried out by SAS software (Version 9.8). The findings showed that total ash, springiness, elasticity, humidity, water activity and adhesiveness significantly increased with an increase in the Benthosema pterotum gelatin concentration in the pastille samples (p<0.05). However, the best pastille texture was observed in 50% BG 50% FG and for other parameters in samples with 100% BG (p<0.05). According to the results of sensory evaluation and color characteristics of treatments, it can be concluded that 25% Benthosema pterotum gelatin can be added to the bovine gelatin in the pastille formulation. The fish gelatin can be applied as cost-efficient source and also as quality improver in the production of pastilles.

Infectious pancreatic necrosis virus (IPNV) is one of the major worldwide leading causes of losses among different fish species, especially in salmonidae. In order to develop a vaccine (First stage), the VP2 gene from an Iranian IPNV isolate was amplified using polymerase chain reaction (PCR), inserted between SpeI and ScaI restriction sites of pNZ8150 expression vector under the control of NICE promoter, and transformed into electrocompetent Lactococcus lactis cells using electroporation method regarding production of a recombinant live vector vaccine in fish. The transformed L. lactis cells containing the highest copy of the recombinant plasmid, pNZVP2, were selected using high antibiotic concentration (100 μg/mL of chloramphenicol). These cells are expected to express high level of VP2 protein and consequently will be the best candidates for vaccine formulation. Restriction enzyme digestion using SpeI, colony PCR using gene specific primers and boiling method, and DNA sequencing confirmed construction of the recombinant expression vector, pNZVP2. The present research will pave the way for expression and oral delivery of not only IPNV antigens, but also, any other infectious agents via pNZ8150/L. lactis expression system, potentially as a novel platform for the development of oral delivery vaccines in fish.

Shrimp polyculture with carp species has a great potential in economic development of Bangladesh. At present, shrimp polyculture technology is being most extensively used by shrimp farmers in the coastal regions of the country; however, the mechanism of scientific culture system is not well understood. Therefore, to evaluate the economic feasibility of shrimp (Penaeus monodon) polyculture with carp over mix culture of shrimp with prawn (Macrobrachium rosenbergii) and monoculture of shrimp, a study was conducted for a period of six months from July to December 2016 in selected ghers (modified low-lying rice fields with raised dykes, used for seasonal production of shrimp) at Kaliganj Upazila of Satkhira District, Bangladesh. Water quality was within the suitable range for shrimp culture. During the study period, environmental sustainability in terms of soil quality was achieved in polyculture of shrimp with carps and tilapia (Oreochromis niloticus). Growth performance and total yield of shrimp (2087.87±34.47 kg/ha) and prawn (1789.47±27.45 kg/ha) were also significantly (P<0.05) improved in polyculture of shrimp with carps and tilapia compared to shrimp monoculture and mix culture of prawn and shrimp, respectively. The economic sustainability was also found to achieve in polyculture of shrimp with carps and tilapia (Oreochromis niloticus) in terms of the Benefit-cost ratio (BCR), which was significantly (P<0.05) higher (2.49±0.03) compared to other culture systems (1.96±0.06 in shrimp monoculture and 1.26±0.03 in shrimp and prawn mix culture).

Skin protects the body from outer factors as a barrier, and contains an important cosmetic role. Skin aging is related to collagen degradation and increasing multiple enzymes, including matrix metalloproteinase (MMPS), which degrade collagen. Chlorella vulgaris is a marine alga that exhibits anti-aging activity. The beneficial effects of Chlorella on skin make it a proper ingredient to be used in anti-aging products. In this study, the effect of Chlorella growth factor (CGF) on types І and ІІІ collagen in human fibroblast cell line Hu02 was investigated. To find an effective extraction method in the present study, CGF was extracted using hot water extraction, enzymatic hydrolysis, and ultrasonication plus enzymatic hydrolysis, and the yields were compared. The yield of ultrasonication plus enzymatic hydrolysis method (CGF-3) had the strongest absorbance at 260 nm and highest solid recovery, compared to the other two methods. Using quantitative PCR, it was confirmed that CGF increased collagens І and ІІІ expression in skin fibroblast cells. This finding indicated that CGF induced collagen synthesis in Hu02 cells. Gene expression of types І and ІІІ collagen were elevated to 3.144-fold and 1.14-fold in the CGF-3 group, respectively, comparing to the control group.

The family of Anisakidea (Anisakis and Contracaecum) includes zoonotic parasitic nematodes that have worldwide distribution. Two hundreds Anisakis and Contracaecum sp. nematode samples were collected from the intestine of Mesopotamichthys sharpeyi and Barbus grypus caught from Shadegan Wetland, where known as an important international wetland in Iran with a rich biodiversity. After extraction of the genomic DNA, PCR was used to amplify the entire ITS fragment with primers NC5-NC2. PCR products were fractionated by agarose gel electrophoresis prior to purify using gel extraction kit. The purified DNA was sequenced by an Applied Biosystems DNA sequenced in both directions. In order to compare the obtained sequence data with similar sequences from other nematodes, target sequence data were retrieved from the GenBank. The overall prevalence of Anisakis and Contracaecum in the studied fish from Shadegan Wetland was 6% and 9% in Mesopotamichthys sharpeyi and 4% and 6% in Barbus grypus, respectively. All nematodes were identified as Anisakis pegreffii and Contracaecum rudolphii based on the phylogenetic tree and genetic distance. This is the first time to report the distribution of A. pegreffii and C. rudolphii in Mesopotamichthys sharpeyi and Barbus grypus in Shadegan Wetland. Based on the results, the danger of zoonotic anisakid nematodes, including A. pegreffii and C. rudolphii in the studied area is very low.

In this study, S-type rotifer Brachionus plicatilis were enriched with 10 levels (0, 0.001, 0.01, 0.1, 1, 10, 100, 500, 1000 and 1500 mg L-carnitine per L) of L-carnitine supplements dissolved in Chlorella vulgaris culture medium in a 10 mL individual culture trial for 7 days. The initial rotifer density was 1 individual mL-1. The trials were conducted to 200×06 cell mL-1 at food density at 25±1ºC under an axenic condition in the laboratory. L-carnitine enrichment has shown considerable influence on the population growth of rotifer Brachionus plicatilis. As a result, the maximum number of individuals was determined as 1560 ± 10.00 rot./mL in the group enriched with 100 mg/L L-carnitine supplement and the lowest number of individuals was determined 376.67±25.17 rot./mL in the group enriched with 1500 mg/L L-carnitine addition (p<0.05). The maximum growth rate was found to be 0.63±0.02 rot/ day in the group enriched with 100 mg/L L-carnitine addition (p<0.05). The maximum doubling time was 1.31±0.02 rot./ day for the group enriched with 1000 mg/L L-carnitine (p<0.05). The results suggested that L-carnitine could be a positive factor to enhance reproduction and population growth on enriched Brachionus plicatilis under the optimum concentration.

The present study was carried out on digenean infection in two species of mugilid fish (Chelon auratus and Chelon saliens, Risso, 1810) in southern coast of Caspian Sea. One hundred and ninty eight fishes were totally studied. We identified the digenetic trematodes of three families, Haploporidae (adult Digenea), Heterophyidae (Metacercariae), and Diplostomidae (Metacercariae). Eyes, gills, stomach, intestine and pyloric caeca of fishes were infected with Diplostomidae (Diplostomum spathaceum), Heterophyidae (Ascocotyle (Phagicola) longa and Ascocotyle sp.), Haploporidae (Saccocoelium obesum and S. tensum), respectively. The results revealed that the stomach was the most infected organ (P=57%), and there was a significant difference between mean intensity of infection and sampling stations in Haploporidae (X2= 11.6, df= 3, p= 0.009) and Heterophyidae (X2= 10.2, df= 2, p=0.006). There was no significant difference between mean intensity of infection in three years and fish genders. Ascocotyle (Phagicola) longa and Saccocoelium tensum are reported for the first time in Iran. Another noticeable point is that the digenean parasites, which are prevalent in mullets, can cause disease in fishes. They are zoonotic (Ascocotyle (Phagicola) longa) and are important in point of view of ecology, economy and public health.

Marine benthic macrofauna plays an important role in ecosystem processes in the marine benthic zone. This study aims to investigate the biodiversity pattern and identifying benthic macroinvertebrates in the coastal zones of the Persian Gulf and the Gulf of Oman. Two sampling periods were performed in this study; the first: from November 2018 to January 2019 and the second: from December 2019 to January 2020. Sampling was carried out at 19 sites with three replicates (171 samples). A total of 164 species belonging to 85 families and 31 orders were identified. The most abundant families were Ampeliscidae and Apseudidae with mean values of 19.5±42 and 11.1±18 in m2, respectively. The most abundant class were Malacostraca and Polychaeta. The family Nephtyidae with eight identified species was the most in all stations. Amphipholis squamata, Byblis sp., Capitella capitate, and Amphioplus sp. were the significant species that contributed to the differentiation between stations. Furthermore, according to CCA analysis, dissolved oxygen (DO) showed a strong direct relationship with Callianassidae, Anthuridae, Paraonidae, Maeridae, and Corophiidae. Also, a strong indirect relationship was found between Haminoeidae and DO. Turbidity showed a strong direct relationship with Flabelligeridae and as well as weak direct with Cirratulidae. Furthermore, chlorophyll-a showed a strong direct relationship with Nereididae, and other parameters showed a medium direct relationship with Maldanidae and Haminoeidae. The Composition of bed sediment was also showed a strong relationship with macroinvertebrates communities in the study area. The diverse health status was not totally in a good condition and needs to be improved. These findings could be applied in further studies for habitat management and monitoring programs.

The purpose of this study was to investigate the factors affecting consumers and buyers’ attitude toward fish and fishery products packaging in Tehran. For this purpose, after determining the research hypotheses, a questionnaire consisting of 60 questions was designed in two sections: demographic questions and main questions (Likert five-choice scale). The statistical population of the present study was the city of Tehran, in which 5 urban areas were randomly selected and 384 questionnaires (according to the ratio of household population in these areas) were completed. In order to investigate the acceptance or rejection of hypotheses, a conceptual model was designed and implemented using structural equation modeling (LISREL software). The results showed that three hypotheses of significant effect of the insertion of nutritional value (hypothesis 4), cooking (hypothesis 7) and storage methods (hypothesis 8) on fish and fishery products packaging on consumers and buyers’ attitude toward packaging were rejected and five other hypotheses (significant effect of design and color, size and weight, shape and form, material and brand of packaging on consumers and buyers’ attitude toward packaging) were confirmed. In this study, among the factors affecting consumers and buyers’ attitude toward packaging, the highest effect (path) coefficient was related to the effect of design and color factor (0.29). Brand, size and weight, material and shape (and form) were ranked next with path coefficients of 0.24, 0.21, 0.15 and 0.11, respectively. According to the results, fish and fishery products packaging centers, in order to increase sales, should focus most of their activities on design and color, size and weight, material and shape of packaging.

Delay-difference type models (D-DMs) represent a theoretical bridge between classical surplus-production models and data-rich age-structured models. However, periodic changes of recruitment, growth, and mortality rates can also be accounted for in the continuous time delay-difference models (CTDDMs). Such models incorporate biological processes by considering continuous time delays. In the present study, CTDDMs produced realistic outputs for yield, biomass, and biological reference points (BRPs) based on using data from the southern Atlantic albacore fishery. Simulations of predicted biomass or numbers were carried out using fully age-structured information (covering 30 years) and compared with more complicated age-structured production models (ASPMs). The performance of the CTDDMs was also compared with that of a Bayesian surplus production model (BSPM). BSPM estimates of the BRPs, e.g., r, k and MSY, were used as benchmarks for the respective CTDDMs estimates. The assessed maximum sustainable yields by the two models were approximately 21,600 t and 23,500 t, respectively, while the CTDDMs produced more population parameters estimation. The CTDDMs provided reliable prediction of BRPs for sustainable fisheries management and required fewer data than ASPMs. This study have evaluated the applicability and sensitivity of the continuous-time-type D-DM model. The scalability of these models will be discussed in further research.

Several studies on the round sardinella, Sardinella aurita (Valenciennes, 1847) have focused on the identification of stock composition and boundaries, using one method of discrimination. In this study, three approaches (body morphometric, meristic character (vertebrae number) and otolith shape) were applied on the population of round sardinella along the Algerian Coast in the Mediterranean Sea in order to obtain useful information for the management of this resource. 627 specimens were collected from nine locations from December 2018 to January 2019. The linear discriminant analysis (LDA) applied on both body morphometric characters and the otolith shape which indicated significant difference between areas with a low rate of classification success (47% for body morphometric analysis and 37.5% for otolith shape analysis), the misclassification percentage for each sampling location was explained by the proximity of the sites. Grouping samples into three regions according the Algerian coastline division reduced the misclassification rate; the overall random assignment of individuals into their original sample obtained by LDA was 70% for the morphometric characters, and 55% for the otolith shape. However, no significant difference was found between areas using the analysis of the number of vertebrae. No significant sexual effects were observed on the body morphometric characters, on the otolith shape and on the number of vertebrae.

A 40-day study was done to evaluate the effect of different feeding strategies on growth performance, hematological, and morphological indices in juvenile beluga (Huso huso). For this purpose, one hundred and eighty fish with a mean weight of 34.58±5.32 g were divided into four feeding strategies: F) fed throughout the 40 days, SRF1) 4 intermittent periods of 2-day starvation, 8-day feeding, SRF2) 2 intermittent periods of 4-day starvation, 16-day feeding, SRF3) an 8-day starvation and 32-day feeding. After 40 days, the results showed that some blood indices, including albumin, globulin, cholesterol, and triglyceride levels were not significantly affected by starvation and re-feeding (p>0.05). A significant change was observed in glucose level between treatments and SRF3 had the lowest glucose level. There were significant difference in immunoglobulin levels among treatments (p<0.05). A significant decrease was observed in cortisol levels in starvation and re-feeding treatments compared to the control group (p<0.05). No significant difference was observed in the hepatic and gastrointestinal index (p>0.05). These findings showed that short-term starvations of beluga had no significant negative effect on most biochemical and hematological indices. The results indicated that beluga has the metabolic regulation capability for short periods of starvation.

Harmful blooms of dinoflagellates in southeastern Iran have been increased in recent years. A dense bloom of dinoflagellate species occurred in the Ramin coast after South West Monsoon (SWM) in southeastern Iran. In order to molecular and morphological species identification of the bloom, sampling was done in October 2017, in the phycolab; the dominant bloom-forming species was isolated into a unialgal culture and kept under 12L: 12D and 25°C. The result showed the dominant bloom-forming species belonged to the genus Gonyaulax that co-occurred with the Levanderina fissa, Scrippsiella trochoidea, and Prorocentrum micans species with the lower density. Phytoplankton density was 15×106 cells l-1. Morphological features and nucleotide sequences of the species were similar to Gonyaulax polygramma with 97% bootstrap support. This is the first record of a red tide incident triggered by G. polygramma in the northern Oman Sea, which was associated with changed water color and foam formation. This species is cosmopolitan in coastal waters, which can form harmful algal blooms (HABs).

The bacterial L-asparaginase (ASNase) has been used in the treatment of asparagine-associated tumors; however, the instability of the enzyme increases the number of injections as well as the side effects. In the present study, ASNase was conjugated to nanochitosan (ASNase -CSNPS) by direct (shiff-base) and indirect (glutaraldehyde linker) methods. In order to get the optimal conjugation, ASNase/CSNPS ratio was first investigated. The physicochemical properties (optimum pH, temperature, residual activity), enzyme kinetics (Michaelis constants; Km and maximal velocity; Vmax) and stability (against freezing, proteolysis, and chemical denaturation) were determined. The results showed that the highest residual enzyme activity (>85%) was obtained using a combination of ASNase and CSNPS at 1:5 mass ratio in both conjugation methods. ASNase -CSNPS prepared by glutaraldehyde linker had higher Km and Vmax values (69.7 μM, 20.6 mol/mL/minμ), wider range of optimum pH and higher temperature stability compared to ASNase-CSNPS produced by Schiff-base (Km: 105.8 μM, Vmax 14.5 mol/ml/minμ) method. ASNase-CSNPS produced by indirect method had more stability against freezing-thawing, and proteolysis when compared with ASNase-CSNPS prepared using direct method. The results showed that application of glutaraldehyde coupling was superior to Schiff base cross linking for conjugating of ASNase to CSNPS and for production of ASNase with better physicochemical properties for future cancer therapy.

The antibacterial activity of oregano (Origanum vulgare) essential oil (OEO), carvacrol and thymol was tested against seven Gram-negative and nine Gram-positive fish pathogenic bacteria isolated from cultured olive flounder (Paralichthys olivaceus) in Korea. Disk diffusion assay, MIC (minimum inhibitory concentration) and MBC (minimum bactericidal concentration) tests showed OEO, carvacrol and thymol inhibiting the growth of both Gram-negative and Gram-positive bacteria. Carvacrol and thymol showed lower MIC values than OEO against every isolate which ranged from 0.001 to 0.007 % (V/V) and 0.001 to 0.062 % (V/V), respectively. Carvacrol (MBC/MIC= 1-4) and thymol (MBC/MIC= 2-4) were bactericidal for all tested strains while OEO (MBC/MIC= 2-8) was being both bactericidal and bacteriostatic. In every fish pathogenic bacteria, the inhibition zone diameter (IZD) increased in proportion to the oil concentration and the maximum effect was found at 100 % (V/V) concentration of OEO, carvacrol and thymol. The antibiogram pattern indicated that all the bacterial strains excluding three strains of S. iniae (S186, S530, and S131) showed resistance to one or more antibiotics. The percentage of relative inhibition zone diameter (RIZD %) exhibited high values at higher concentration of all agents. Since antibacterial activities of OEO, carvacrol and thymol were considerably effective against fish pathogenic bacteria, their use could be alternatives to treat bacterial infections in aquaculture.

This study was designed to evaluate the differences in haematological parameters of males and females of cultured hybrid striped bass (Morone chrysops X Morone saxatilis) (Walbaum, 1752). Fish used in the research were cultured in a recirculating aquaculture system (RAS) of a Sicilian farm in Italy. A total of 160 mature fish (80 males and 80 females) were collected, and blood samples were taken from the caudal vein. Haematological parameters were measured. Weight and total length of fish were also registered. The unpaired t- test statistical method was applied to compare each parameter in the two sexes. In our findings, three haematological parameters: white blood cells WBC (♂ 16.09 ± 7.86; ♀ 20.25 ± 4.62; P < 0.05), mean corpuscular haemoglobin MCH (♂; 24.95 ± 2.92; ♀ 23.46 ± 2.56; P < 0.05) and thrombocytes TC (♂ 53.89 ± 15.06; ♀ 34.03 ± 9.89; P < 0.0001) revealed significant differences between male and female fish. On the contrary, no significant differences were observed in biometric indices and red blood cells, haemoglobin concentration, haematocrit and mean corpuscular volume. Results obtained from our research helps to evaluate the influence of sex on haematology of hybrid striped bass and, consequently, for monitoring changes in the health status of fish.This study was designed to evaluate the differences in haematological parameters of males and females of cultured hybrid striped bass (Morone chrysops X Morone saxatilis) (Walbaum, 1752). Fish used in the research were cultured in a recirculating aquaculture system (RAS) of a Sicilian farm in Italy. A total of 160 mature fish (80 males and 80 females) were collected, and blood samples were taken from the caudal vein. Haematological parameters were measured. Weight and total length of fish were also registered. The unpaired t- test statistical method was applied to compare each parameter in the two sexes. In our findings, three haematological parameters: white blood cells WBC (♂ 16.09 ± 7.86; ♀ 20.25 ± 4.62; P < 0.05), mean corpuscular haemoglobin MCH (♂; 24.95 ± 2.92; ♀ 23.46 ± 2.56; P < 0.05) and thrombocytes TC (♂ 53.89 ± 15.06; ♀ 34.03 ± 9.89; P < 0.0001) revealed significant differences between male and female fish. On the contrary, no significant differences were observed in biometric indices and red blood cells, haemoglobin concentration, haematocrit and mean corpuscular volume. Results obtained from our research helps to evaluate the influence of sex on haematology of hybrid striped bass and, consequently, for monitoring changes in the health status of fish.This study was designed to evaluate the differences in haematological parameters of males and females of cultured hybrid striped bass (Morone chrysops X Morone saxatilis) (Walbaum, 1752). Fish used in the research were cultured in a recirculating aquaculture system (RAS) of a Sicilian farm in Italy. A total of 160 mature fish (80 males and 80 females) were collected, and blood samples were taken from the caudal vein. Haematological parameters were measured. Weight and total length of fish were also registered. The unpaired t- test statistical method was applied to compare each parameter in the two sexes. In our findings, three haematological parameters: white blood cells WBC (♂ 16.09 ± 7.86; ♀ 20.25 ± 4.62; P < 0.05), mean corpuscular haemoglobin MCH (♂; 24.95 ± 2.92; ♀ 23.46 ± 2.56; P < 0.05) and thrombocytes TC (♂ 53.89 ± 15.06; ♀ 34.03 ± 9.89; P < 0.0001) revealed significant differences between male and female fish. On the contrary, no significant differences were observed in biometric indices and red blood cells, haemoglobin concentration, haematocrit and mean corpuscular volume. Results obtained from our research helps to evaluate the influence of sex on haematology of hybrid striped bass and, consequently, for monitoring changes in the health status of fish.This study was designed to evaluate the differences in haematological parameters of males and females of cultured hybrid striped bass (Morone chrysops X Morone saxatilis) (Walbaum, 1752). Fish used in the research were cultured in a recirculating aquaculture system (RAS) of a Sicilian farm in Italy. A total of 160 mature fish (80 males and 80 females) were collected, and blood samples were taken from the caudal vein. Haematological parameters were measured. Weight and total length of fish were also registered. The unpaired t- test statistical method was applied to compare each parameter in the two sexes. In our findings, three haematological parameters: white blood cells WBC (♂ 16.09 ± 7.86; ♀ 20.25 ± 4.62; P < 0.05), mean corpuscular haemoglobin MCH (♂; 24.95 ± 2.92; ♀ 23.46 ± 2.56; P < 0.05) and thrombocytes TC (♂ 53.89 ± 15.06; ♀ 34.03 ± 9.89; P < 0.0001) revealed significant differences between male and female fish. On the contrary, no significant differences were observed in biometric indices and red blood cells, haemoglobin concentration, haematocrit and mean corpuscular volume. Results obtained from our research helps to evaluate the influence of sex on haematology of hybrid striped bass and, consequently, for monitoring changes in the health status of fish.