Tilapia Species Research Articles

Trophic niche variation driven by water level fluctuations facilitates the co-occurrence of invasive tilapia species in a subtropical reservoir in China.

Investigating how multiple invasive fish species with similar ecological traits respond to different environmental conditions is crucial to understanding their successful invasion and coexistence. Here, we used stomach content analysis and stable isotope analysis to analyse the effects of water level fluctuation on the trophic niche plasticity of three dominant co-occurring invasive tilapia species (Coptodon zillii, Sarotherodon galilaeus, and Oreochromis niloticus) in the Shanmei Reservoir, southern China. We found that the tilapia species exhibited an iliophagous habit with dietary variations between the high-water (HW) and low-water (LW) level periods. During the LW period, tilapia fishes primarily fed on periphytic algae, whereas during the HW period, they reduced their consumption of epiphytic algae and increased their intake of plant remains. Biofilms were the most assimilated resource by the species during the LW period, whereas riparian plants dominated during the HW period. The niche width and niche overlap of the three tilapia species were significantly greater in the HW period than in the LW period. However, their trophic positions were not significantly affected by water level fluctuations. Our findings indicate that temporal variation in diet composition and trophic niche, driven by water level fluctuations, may favor food resource partitioning and facilitate the coexistence of these invasive tilapia species.

Pathological effects and immune modulation in host during Tilapia Parvovirus (TiPV) outbreak in cage and wetland Tilapia farms.

Viral diseases arising in farmed fish are an ongoing challenge to the aquaculture industry, causing severe mortality and economic losses. Recently, there has been a spike in the incidence of a viral disease caused by Tilapia Parvovirus (TiPV) inflicts irreparable damage, and large-scale fish kills in the farmed tilapia species. We investigated a case of disease outbreak and severe mortality in cage and wetland farms of tilapia in West Bengal and Odisha, India. The symptomatic fish showed clinical signs, including hemorrhage, discoloration, ulcer, and redness in the body surfaces. Further analysis revealed that Tilapia Parvovirus was associated (validated by PCR, phylogenetic analysis, and cell line assay) with the infection and mortality of tilapia. The virus was detected in gill, heart, spleen, liver, and kidney samples collected from apparently healthy (asymptomatic) and symptomatic tilapia samples from cage and wetland farms. At the same time, negative results were found in the brain and skin tissue samples. The histological analysis revealed that TiPV induces severe damage invariably in almost all studied tissue, including the liver, kidney, spleen, gill, heart, and brain of tilapia samples. The viral quantification analysis showed that the viral genome was higher in the liver, spleen, and heart than in the tilapia samples' gill, kidney, or brain tissue. Furthermore, the study indicated that TiPV infection has a significant effect on the health of tilapia. The tilapia exhibited an immune reactivity toward TiPV infection (upregulation of chemokine receptors, CRs and interleukin 1β, IL-1β), the majority of the studied immune genes (interleukin 8, IL-8; Toll-like receptors 7, TLR7; tumour necrosis factor α, TNF-α; major histocompatibility complex II, MHC II and nuclear factor kappa B, NF-kB) were significantly downregulated in the kidney, spleen and liver tissue samples of symptomatic tilapia. Further, the in vivo challenge assay confirms that the isolated TiPV is a novel parvovirus pathogen that causes massive mortality in tilapia. The lessons learned from the first cellular and molecular description associated with TiPV epidemiology from wetland and cage farms of tilapia could be critical to developing the current state of the tilapia farming industry. Additionally, a holistic approach is needed to develop management measures to control the virulence and risk factors of TiPV.

Flux profile of selenium intake and dietary health assessment of tilapia products in China e-commerce platform

Tilapia is known as an important way to obtain selenium and has high nutritional values for humans. However, there is currently no specific analysis of the flux profile of selenium intake and dietary health evaluation in tilapia. In addition, it is important for consumers to obtain relevant assessments of the selenium content in different species of tilapia. This will enable different age groups to plan their dietary intake in an organized manner accordingly. We counted the total import and export volume of tilapia in China. Furthermore, we modeled the distribution of selenium content based on the production mode on this basis. The study also delved into the distribution pattern of selenium content within China (n=147). Guangdong, as the production place of tilapia, is the largest e-commerce channel for consumers. The median selenium measured in frozen tilapia, pickled tilapia and canned tilapia was 0.233 mg/kg, 0.239 mg/kg and 1.073 mg/kg respectively. It is evident that adults globally should regulate their consumption of canned tilapia to avoid selenium toxicity. Furthermore, relying solely on tilapia consumption is insufficient to meet the selenium needs of infants. The findings underscore the nutritional value of tilapia in diets. Additionally, these insights can facilitate a comprehensive assessment of the health implications associated with dietary choices, enabling the formulation of targeted advice for various age groups worldwide.

Analysis of the pharyngeal structure of the genus Oreochromis for species identification through geometric morphometrics in the Aguamilpa reservoir, Nayarit, Mexico

Tilapia is an important fishing resource in economic terms for continental ecosystems such as dam reservoirs and lagoons. In Nayarit, the Aguamilpa Dam reservoir contributes around 50 % of the tilapia production in the state. However, despite the social and economic importance of the resource, there are few studies on it in this reservoir, and it is still unknown with certainty which species are found in the reservoir. This work is the first report for the Aguamilpa reservoir, where geometric morphometrics was used as a tool for the identification of tilapia species. The pharyngeal plate of 230 organisms was used for the geometric morphometrics analysis. According to this study, the existence of three species of the genus Oreochromis (O. aureus, O. niloticus and Oreochromis mossambicus) is confirmed; according to the analysis of canonical variables, the three species were correctly discriminated. This allows us to conclude that the use of geometric morphometrics in the pharyngeal plate is a useful structure for the identification of species in the reservoir.

Exploring the presence of tilapia species in a central western Mexican reservoir using mitochondrial DNA control region sequencing

Oreochromis niloticus is the most important aquacultural species worldwide. Several countries are interested in repopulating natural or artificial reservoirs with the fry of tilapia (Oreochromis sp.) to develop new fisheries or to enhance the existing ones. However, as tilapia is considered an invasive species, it is essential to check the existence of the species in the place before releasing any fry. Characterization of tilapia species with meristic is unreliable because of existing morphological similarities among species. In this work, the composition of the tilapia species of Laguna El Mastranzo (LEM), Nayarit, Mexico, was explored for the first time through a molecular method using the mitochondrial DNA control region. Three tilapia species (Oreochromis niloticus, O. aureus, and O. urolepis) were found in LEM, and it was confirmed that the two commercial strains (Aquamol and Spring) intended for repopulation were O. niloticus. Seven haplotypes of mitochondrial DNA control region sequences were obtained: three in LEM, three in Aquamol, and one in Spring strains. Before repopulating any reservoir, a molecular verification strategy is recommended to avoid spreading the species. The results of this work represent a glimpse into the genetic material of LEM, Nayarit, Mexico.

First report of Oreochromis niloticus in the Sonora River, Mexico

Commercial farming of tilapia species has been spread to many countries worldwide to meet the need for animal protein at an affordable price, which has led tilapias to invade natural areas. Consequently, tilapias have established wild populations, causing a great negative impact on native biodiversity. The Sonora River, located in northwest Mexico, has an approximate length of 400 km, and at least four native fish species inhabit it. Nevertheless, the Sonora River has been severely reduced and contaminated by open-pit mining. According to existing knowledge, the presence of tilapias is not reported in the Sonora River; hence, the present study is the first report of the presence of the Nile tilapia Oreochromis niloticus in a site near the town of Baviácora, Sonora, Mexico. The presence of this invasive species may represent a severe threat to the biotic component of this ecosystem, which is already affected by mining pollution.

Heavy metals in wastewater and fish collected from waste stabilization pond and human health risks in southwestern Ethiopia

IntroductionThis study aimed to measure the concentration of toxic heavy metals in wastewater samples and Nile tilapia (Oreochromis niloticus) species inhabiting wastewater (waste stabilization ponds) and evaluate their safety as a food source in southwestern Ethiopia. For this purpose, toxic metals like lead (Pb), cadmium (Cd), arsenic (As), and mercury (Hg) in wastewater samples and fish tissues (muscle, gill, and liver) were independently examined.MethodsA laboratory-based cross-sectional study was performed to ascertain the levels of Pb, Cd, As, and Hg in the fish tissues of O. niloticus and wastewater samples. Heavy metal levels were analyzed by microplasma atomic emission spectrometry (Agilent 4210 MP-AES) and hydrogen-generated atomic absorption spectrometry (HGAAS, novAA 400P, Germany).ResultsHeavy metal concentrations were measured in the following decreasing order (µg L−1): Cd > Pb > As > Hg in facultative and maturation ponds, with Cd (27.66 µg L−1) having the highest concentration and Hg (0.349 µg L−1) having the lowest concentration. Among the heavy metals detected in the wastewater samples, Hg showed a statistically significant difference between the sampling points (p = 0.023). The maximum metal concentration was measured for Pb (0.35 mg kg−1) and Cd (0.24 mg kg−1) in the muscle tissue of O. niloticus. The value of arsenic (0.02 mg kg−1) detected in fish edible muscles exceeded the FAO/WHO maximum permissible limit (MPL = 0.01) for human consumption. The carcinogenic and non-carcinogenic health risks of consuming fish due to trace metals were relatively low and posed fewer potential threats to human health. According to this finding, children were more susceptible to heavy metal exposure than adults.ConclusionDue to the high quantities of these harmful heavy metals, wastewater from oxidation ponds should not be used for fishing to avoid bioaccumulation. The target carcinogenic risk (TR) and target hazard quotient (THQ) indicated that all heavy metals were below the safe threshold. This research will provide a baseline for monitoring trace metals in various edible aquatic creatures and for future research in artificial habitats and regulatory considerations.

A novel automated approach for fish biomass estimation in turbid environments through deep learning, object detection, and regression

Estimating fish biomass is crucial in the fisheries sector, where traditional methods often harm fish through manual sampling and anesthetics. A non-invasive approach is introduced using underwater films to estimate fish biomass in turbid conditions. This study presents the “Aquatic WeightNet” dataset, targeting the Genetically Improved Formed Tilapia (GIFT) Tilapia species, and addresses the challenge of unclear images with preprocessing techniques like dehazing and Contrast Limited Adaptive Histogram Equalization (CLAHE). YOLOv8, a leading object detection model modified to accommodate the custom Aquatic WeightNet dataset's varied image sizes with five detection heads, P2 to P6, is employed, achieving a recall of 0.997 and a mean Average Precision (mAP) of 0.899 within the 50–95% Intersection over Union (IoU) range. Fish biomass estimation assesses depth, length, and width using regression models for calculation. A three-phase grid search identifies the most effective models, with the Extra Trees Regressor outperforming depth estimation with mean absolute error (MAE) of 0.63 and coefficient of determination (R2) of 0.87 and the Random Forest Regressor for length and width (MAE of 0.01 and R2 of 0.99). For biomass estimation, the Extra Trees Regressor again performs well (MAE of 0.004 and R2 of 0.99), which is critical for determining optimal feed quantities to enhance aquaculture efficiency. This study emphasizes a non-invasive method to estimate fish biomass, optimizing the effectiveness and ecological sustainability of fish farming in murky waters through advanced detection algorithms and robust regression models.

Bentonite Clays as Adsorbent Material for Mycotoxins and the Hematological Parameters Involved in Tilapia Species: A Systematic Review

Bentonite Clays as Adsorbent Material for Mycotoxins and the Hematological Parameters Involved in Tilapia Species: A Systematic Review

The Recent Trends of the Inland Fishery of Basrah Government, Iraq

The fish species caught in the inland fishery of Basrah were recorded from seven landing sites between January and December 2022. A total of 14 types of fish from four families were identified in this fishery. The most commonly caught fish were exotic species such as Cyprinus carpio and tilapia species. In contrast, the landings of significant native freshwater fish that are characteristic of Mesopotamian aquatic environments, such as Carasobarbus luteus, Mesopotamichthys sharpeyi, Luciobarbus xanthopterus, and Arabibarbus grypus, dropped considerably. The total fish landing has been steadily increasing since 2009, indicating a positive trend in the overall landing. This growth may be attributed to the expansion of fishing activities and the prevalence of exotic species due to the degradation of the water ecosystem in Southern Iraq. From a fisheries management viewpoint, it is essential to maintain native stocks in the aquatic ecosystems in southern Iraq involving regional cooperation between Iraq, Turkey and Iran to secure the appropriate quantities of water for Iraq from the upper Tigris and Euphrates Rivers, strengthening the stocks of economically native fish by artificially propagating them and then releasing juvenile species into natural waters, and restrict the reproduction of carps and confining them to fish farms, and finally minimizing the impacts of tilapia species by intensifying the fishing activities.

Effect of biofloc technology at varies biological factors on the growth performance and water quality in cultivation of red hybrid tilapia

Aquaculture is one of the important food-producing sectors. However, the effluent of the aquaculture system consists of pollutants such as nitrogenous compounds and the ample usage of water for traditional aquaculture systems. Therefore, biofloc technology was developed in the aquaculture industry in the 1980s to improve the water quality of the system and increase the fish production. The purpose of this experimental work is to investigate the effect of biological factors on the growth performance of fish and the water quality of the biofloc technology (BFT) aquaculture system for red hybrid tilapia cultivation. In this study, 3 biological factors such as the carbon-to-nitrogen ratio, stocking density and the feeding rate were studied under BFT. Parallel experiments in thirteen suspended growth tanks were carried out within (10:1-20:1) C/N ratio, (1%-5%) feeding rate and (20-80 fish m-3) stocking density for 10 weeks. Growth rate of fish and water quality data such as ammonia, nitrite and nitrate concentrations were collected weekly during the study. The results revealed that the 20:1 C/N ratio gave the best water quality. Feeding rate at 4% of body weight produced good growth performance of the tilapia species and the higher stocking densities lead to lower water quality and survival rate.

Polyculture potential of endemic Benni (Mesopotamichthys sharpeyi) with three species of non-endemic tilapia, Zilli (Captodon zilli), Blue (Oreochromis aureus), and Nile (Oreochromis niloticus) based on various weight ratios and stocking densities

This study aimed to investigate Benni's weight ratios or stocking densities in two distinct experiments in the presence of three species of tilapia: Zilli, Blue, and Nile in 60 days. The fish were divided into four experimental groups with 22 treatments in triplicate. The groups were based on different weight ratios (10% or 30% difference) and stocking densities (2:1, 1:2, and 1:5). This included four control treatments, six Benni-Zilli treatments, six Benni-Blue treatments, and six Benni-Nile treatments. Benni, Zili, Blue, and Nile had initial weight ranges of 5.1–9.3, 4.0–7.2, 5.1–9.2, and 5.1–7.7 g, respectively. Benni's growth performance compared to Zilli had a direct relationship with Benni's weight gain. A reverse correlation was revealed with Benni's weight gain in the analysis of Zilli's growth performances. Benni and Zilli showed similar growth performances during the stocking density experiment. Treatments with higher weight and stocking density ratios of Benni showed an improved survival rate. The highest survival rate for Zilli was observed in Benni's lower weight and stocking density ratios. Various weight ratios and stocking density had no significant effect on Benni's growth compared to Blue. The growth performance of Blue in Beni-Blue experimental treatments was better than that of Benni. In all six Benni-Blue treatments, the average survival rate of Benni was 97.76%, while Blue was 94.41%. The experimental treatments with Benni-Nile showed no adverse effect of increasing the stocking density ratio of Benni on Nile growth performance. The Benni population increased, and Nile growth indicators improved. These results suggest that the Nile exhibits high competition ability against Benni. It is noticeable that the Benni did not achieve a 100% survival rate in any Benni-Nile treatment, while the Nile had a 100% survival rate in the four experimental treatments. According to the results, the presence of Nile, Zilli, and Blue had the most negative impacts on the growth indices of Benni, respectively. Moreover, Benni showed the highest average survival rate in polyculture with Blue, Zilli, and Nile, respectively. Benni cannot compete interspecies with tilapia by species-based mechanisms. Benni in polyculture with Nile tilapia is not advised under the experimental conditions. The negative impacts of Zilli's presence next to Benni may be reduced by increasing the weight ratio or stocking density. Blue demonstrated the least negative impact on the examined Benni performances compared to the other two experimental tilapia. It is recommended that every effort be made to prevent the introduction of any tilapia species into Benni's ecosystem.

Identification and characterization of motile Aeromonas spp. isolated from farmed Nile tilapia (Oreochromis niloticus) in the Philippines.

Motile Aeromonas septicaemia (MAS) caused by motile Aeromonas species is an important disease in farmed freshwater fish due to intensification of culture and improper farm practices. This study characterized and profiled motile Aeromonas species recovered from clinically sick tilapia farmed in the Philippines, with a view to identifying targeted disease prevention and control measures against MAS in farmed tilapia species. Sixteen isolates from diseased farmed Nile tilapia were identified as Aeromonas veronii (n=14), Aeromonas caviae (n=1), and Aeromonas dhakensis (n=1). Five biochemical profiles using API 20E were exhibited by the A. veronii strains giving an unreliable identification. A high level of agreement was observed in identifying the Aeromonas strains using 16S rRNA and rpoD gene sequencing, although the latter has a higher discriminatory value. Three or more virulence genes dominated by cytotoxic enterotoxin act and aerolysin aer were detected. Different genotypes based on virulence gene clustering suggested varied mechanisms used by Aeromonas to colonize and infect or to mutualistically co-exist with the fish. Acquired multiple antibiotic resistance was found in a single A. veronii isolate. All were susceptible to enrofloxacin, oxolinic acid, florfenicol, and chloramphenicol. Tetracycline and sulfonamide resistances and class 1 integron were detected in three A. veronii isolates. Several strains of motile aeromonads, especially A. veronii, which have varied genotypes based on virulence, biochemical profile, and antibiotic resistance, are involved in MAS in natural disease outbreaks in farmed Nile tilapia in the Philippines.

First report on chemometric modeling of tilapia fish aquatic toxicity to organic chemicals: Toxicity data gap filling

The Toxic Substances Control Act (TSCA) mandates the Environmental Protection Agency (EPA) to document chemicals entering the US. Due to the vast range of toxicity endpoints, experimental toxicological study for all chemicals is impossible to conduct. To address this, in silico methods like QSAR and read-across are strategically used to prioritize testing for chemicals lacking ecotoxicity data. Aquatic toxicity is one of the most critical endpoints directly related to aquatic species, mainly fish, followed by direct to indirect effects on humans through drinking water and fish as food, respectively. Therefore, we have employed the ToxValDB database to curate acute LC50 toxicity data for three Tilapia species covering two different genera, an ideal species for aquatic toxicity testing. Employing the curated dataset, we have developed multiple robust and predictive QSAR and quantitative read-across structure-activity relationship (q-RASAR) models for Tilapia zillii, Oreochromis niloticus, and Oreochromis mossambicus which helped to understand the toxicological mode of action (MoA) of the modeled chemicals and predict the aquatic toxicity of new untested chemicals followed by toxicity data gap filling. The best three QSAR models showed encouraging statistical quality in terms of determination coefficient R2 (0.94, 0.74, and 0.77), cross-validated leave-one-out Q2 (0.90, 0.67 and 0.70), and predictive capability in terms of R2pred (0.95, 0.77, and 0.74) for T. zillii, O. niloticus, and O. mossambicus datasets, respectively. The developed best mathematical models were used for the prediction of aquatic toxicity in terms of pLC50 for 297 untested organic chemicals across three major Tilapia species ranging from 1.841 to 8.561 M in terms of environmental risk assessment.

Diet-habitat ecology of invasive tilapia and native fish in a tropical river catchment following a tilapia invasion

Many species of tilapia (a collection of fish species from the cichlidae family) have biological traits that make them successful invaders. Widespread herbivory has been observed across tilapia species, however knowledge on habitat preferences and tilapia interactions with native fish food webs is limited. This study was conducted three years after spotted (Pelmatolapia mariae) and Mozambique (Oreochromis mossambicus) tilapia were detected in the Mitchell River catchment, northern Australia. Tilapia diet and habitat preferences and their trophic position in native fish food webs was determined using a combination of stomach content, stable isotope, and habitat assessment analyses. Plant material was the most abundant item in tilapia stomachs, and some stomachs also contained other items in small quantities, such as fish eggs, small shrimp, and bivalves. Some niche overlap occurred between P. mariae and native omnivore or herbivore fish species. Macrohabitat type (in-channel (no tilapia), floodplain (no tilapia), weir (tilapia present)) was related to native fish food web structure, with weir food webs showing similarities to floodplain food webs. Floodplain habitats including creeks and wetlands were also most similar to weir habitats and may therefore be most at risk of colonization as tilapia spread throughout the catchment. This study clearly demonstrated that the successful rapid invasion of these two tilapia species is linked to suitable habitat with abundant food that fuels growth and reproduction. These findings increase understanding of diet related habitat use during new tilapia invasions and trophic interactions with native species.

Microbiota plasticity in tilapia gut revealed by meta-analysis evaluating the effect of probiotics, prebiotics, and biofloc.

Tilapia species are among the most cultivated fish worldwide due to their biological advantages but face several challenges, including environmental impact and disease outbreaks. Feed additives, such as probiotics, prebiotics, and other microorganisms, have emerged as strategies to protect against pathogens and promote immune system activation and other host responses, with consequent reductions in antibiotic use. Because these additives also influence tilapia's gut microbiota and positively affect the tilapia culture, we assume it is a flexible annex organ capable of being subject to significant modifications without affecting the biological performance of the host. Therefore, we evaluated the effect of probiotics and other additives ingested by tilapia on its gut microbiota through a meta-analysis of several bioprojects studying the tilapia gut microbiota exposed to feed additives (probiotic, prebiotic, biofloc). A total of 221 tilapia gut microbiota samples from 14 bioprojects were evaluated. Alpha and beta diversity metrics showed no differentiation patterns in relation to the control group, either comparing additives as a group or individually. Results also revealed a control group with a wide dispersion pattern even when these fish did not receive additives. After concatenating the information, the tilapia gut core microbiota was represented by four enriched phyla including Proteobacteria (31%), Fusobacteria (23%), Actinobacteria (19%), and Firmicutes (16%), and seven minor phyla Planctomycetes (1%), Chlamydiae (1%), Chloroflexi (1%), Cyanobacteria (1%), Spirochaetes (1%), Deinococcus Thermus (1%), and Verrucomicrobia (1%). Finally, results suggest that the tilapia gut microbiota is a dynamic microbial community that can plastically respond to feed additives exposure with the potential to influence its taxonomic profile allowing a considerable optimal range of variation, probably guaranteeing its physiological function under different circumstances.

Comparative transcriptomes reveal different tolerance mechanisms to Streptococcus agalactiae in hybrid tilapia, nile tilapia, and blue tilapia

Tilapia is one of the most economically important freshwater fish farmed in China. Streptococcosis outbreaks have been extensively documented in farmed tilapia species. Hybrid tilapia (Oreochromis niloticus ♀ × O. aureus ♂) exhibit greater disease resistance than Nile tilapia (O. niloticus) and blue tilapia (O. aureus). However, the molecular mechanism underlying the enhanced tolerance of hybrid tilapia is still poorly understood. In this study, comparative transcriptome analysis was performed to reveal the different tolerance mechanisms to Streptococcus agalactiae in the three tilapia lines. In total, 1982, 2355, and 2076 differentially expressed genes were identified at 48 h post-infection in hybrid tilapia, Nile tilapia, and blue tilapia, respectively. Functional enrichment analysis indicated that numerous metabolic and immune-related pathways were activated in all three tilapia lines. The differential expression of specific genes associated with phagosome, focal adhesion, cytokine–cytokine receptor interaction, and toll-like receptor signaling pathways contributed to the resistance of hybrid tilapia. Notably, immune response genes in hybrid tilapia, such as P38, TLR5, CXCR3, CXCL12, PSTPIP1, and TFR, were generally suppressed under normal conditions but selectively induced following pathogen challenge. These results expand our knowledge of the molecular mechanisms underlying S. agalactiae tolerance in hybrid tilapia and provide valuable insights for tilapia breeding programs.

Comparative analysis of quantitative phosphoproteomics between two tilapias (Oreochromis niloticus and Oreochromis aureus) under low-temperature stress.

As an important farmed fish, tilapia has poor tolerance to low-temperatures. At the same time, different tilapia strains have apparent differences in low-temperature tolerance. In this study, using the iTRAQ method, the phosphorylated proteomics of two tilapia strains (Oreochromis niloticus and Oreochromis aureus) with different tolerances to low-temperature stress were quantitatively and comparatively analyzed, to clarify the physiological mechanism of tilapia's response to low-temperature stress. Through the GO and IPR analyses of differentially phosphorylated proteins, a number of similarities in physiological activities and regulatory effects were found between the two tilapias in response to low-temperature stress. Many differentially phosphorylated proteins are mainly involved in lipid metabolism, cell proliferation and apoptosis. However, the difference in endurance of low temperature of these two tilapias might be related to the differences in categories, expression and modification level of genetic products which were involved in the aforementioned physiological processes. And meanwhile, the enrichment results of KEGG showed the changes of multiple immune-related and growth-related phosphorylated proteins in the cytokine-cytokine receptor interaction pathway in O. aureus are more prominent. Furthermore, the significantly enriched pathway of carbohydrate digestion and absorption in O. niloticus may indicate that low-temperature stress exerts a more severe impact on energy metabolism. The relative results would help elucidating the molecular mechanism by which tilapia responds to low-temperature stress, and developing culture of tilapia species.

Sharing is caring? Barcoding suggests co-introduction of dactylogyrid monogeneans with Nile tilapia and transfer towards native tilapias in sub-Saharan Africa

Invasive Nile tilapias negatively impact native tilapia species through hybridisation and competition. However, the co-introduction of parasites with Nile tilapia, and subsequent changes in parasite communities, are scarcely documented. Monogeneans are known pathogens of cultured Nile tilapia, although little is known about their fate once Nile tilapias establish in new ecosystems. We investigate the parasitological consequences of Nile tilapia introduction on native tilapias in basins in Cameroon, the Democratic Republic of the Congo (DRC), and Zimbabwe, focusing on ectoparasitic dactylogyrids (Monogenea). Using the mitochondrial cytochrome oxidase c subunit I (COI) and nuclear 18S-internal transcribed spacer 1 (18S-ITS1) rDNA region of 128 and 166 worms, respectively, we evaluated transmission of several dactylogyrid species. Parasite spillover from Nile tilapia was detected for Cichlidogyrus tilapiae to Coptodon guineensis in Cameroon, Cichlidogyrus thurstonae to Oreochromis macrochir in the DRC, and Cichlidogyrus halli and C. tilapiae to Coptodon rendalli in Zimbabwe. Parasite spillback to Nile tilapia was detected for Cichlidogyrus papernastrema and Scutogyrus gravivaginus from Tilapia sparrmanii and Cichlidogyrus dossoui from C. rendalli or T. sparrmanii in the DRC, and Cichlidogyrus chloeae from Oreochromis cf. mortimeri and S. gravivaginus from O. macrochir in Zimbabwe. ‘Hidden’ transmissions (i.e. transmission of certain parasite lineages of species that are naturally present on both alien and native hosts) were detected for C. tilapiae and Scutogyrus longicornis between Nile tilapia and Oreochromis aureus and C. tilapiae between Nile tilapia and Oreochromis mweruensis in the DRC, and Cichlidogyrus sclerosus and C. tilapiae between Nile tilapia and O. cf. mortimeri in Zimbabwe. A high density of Nile tilapia occurring together with native tilapias, and the broad host range and/or environmental tolerance of the transmitted parasites, are proposed as factors behind parasite transmission through ecological fitting. However, continuous monitoring and the inclusion of environmental variables are necessary to understand the long-term consequences of these transmissions on native tilapias and to elucidate other underlying factors influencing these transmissions.

The Transmission of Pseudomonas putida in Some Tilapia species in Egypt: The Potential Role of Clinostomum Infestation

The Transmission of Pseudomonas putida in Some Tilapia species in Egypt: The Potential Role of Clinostomum Infestation