Mugil Cephalus Research Articles

Evaluation of the Heavy Metals Pb, Cd, and Fe in Muscles, Liver, and Skin of Mugil cephalus (Mugilidae) from Tubrukharbor, Eastern Libya

Heavy metal concentrations Lead Pb, Cadmium Cd, and Iron Fe) were determined in the muscles, liver, and skin of Mugil cephalus (Mugilidae) in Tobrukharbor, eastern Libya. The results revealed that the concentration of Pb reached high levels in the skin, while recorded low levels in the liver tissues. Pb level in the liver, skin, and muscle tissues of Mugil cephalus was more than the international standards. The high concentration of Fe recorded in the liver tissue, while, recorded its low concentration in the skin. Also, maximum levels of Cd were detected in the liver, while it attained their low level in the muscles. Generally, the level of Pb and Fe in muscle tissues of Mugil cephalus was more than the international standard and the level of Cd in muscle tissue of Mugil cephalus was lower than the general standard. On the other hand, heavy metals concentration levels in seawaterofTobrukharbor, eastern Libya, exhibited a high level for Fe then Pb comparing to the level of Cd. The relationship between size and weight of Mugil cephalus and the levels of each metal was studied

Involvement of sphaeractinomyxon in the life cycle of mugiliform-infecting Myxobolus (Cnidaria, Myxosporea) reveals high functionality of actinospore morphotype in promoting transmission.

Four new actinospore types belonging to the sphaeractinomyxon collective group (Cnidaria, Myxosporea) are described from the coelomic cavity of a marine Baltidrilus sp. (Oligochaeta, Naididae) inhabiting a northern Portuguese estuary. Host identification supports the usage of marine oligochaetes, namely of the family Naididae Ehrenberg, 1828, as definitive hosts for myxosporeans inhabiting estuarine/marine environments. The absence of mixed infections in the host specimens analysed is suggested to reflect the influence of host-, parasite- and environmental-related factors regulating myxosporean-annelid interactions. Molecular analyses matched the SSU rDNA sequences of three of the four new types with those of mugiliform-infecting Myxobolus spp., namely Myxobolus mugiliensis and a Myxobolus sp. from flathead grey mullet Mugil cephalus, and Myxobolus labrosus from thicklip grey mullet Chelon labrosus. These results directly link, for the first time, the sphaeractinomyxon collective group to a myxospore counterpart, further confirming their previously hypothesized specific involvement in the life cycle of myxobolids that infect mullets. Acknowledging this life cycle relationship, the functionality of the sphaeractinomyxon morphotype is suggested to have been decisive for the evolutionary hyperdiversification of the genus Myxobolus in mullets. Unlike other actinospore morphotypes, sphaeractinomyxon lack valvular processes, which implies a limited capability for buoyancy. Considering the benthic-feeding nature of mullets, this feature is most likely crucial in promoting successful transmission to the vertebrate host.

Immunochemical analysis of pepsin-digested fish tropomyosin

A critical step in determining the allergenicity of a food protein is to study the gastrointestinal digestion resistance, which is an essential characteristic of food allergens due to the preservation of their protein structure and immunoglobulin (Ig) E epitopes. In this study, the immunochemical properties of tropomyosin peptide fragments from Atlantic salmon (Salmo salar) and flathead grey mullet (Mugil cephalus) resulted from pepsin digestion were analyzed. To identify the allergens from salmon and mullet, their IgE- and IgG-binding proteins/peptides were studied using fish-allergic human sera and anti-fish protein monoclonal and polyclonal antibodies. From our results, as the major fish allergen, parvalbumin from both species was recognized in all tested human sera. Tropomyosin-bound IgE was identified in 71% of the tested sera. Antigenicity of intact tropomyosin decreased as a function of pepsin digestion time. The amino acid sequence of mullet tropomyosin was analyzed using a tandem mass spectrometer. Two IgE epitopes on Atlantic salmon tropomyosin alpha-1 were mapped. Overall, tropomyosin was identified as one of the major IgE-binding proteins in both fish species; however, further studies are required to determine the clinical significance of fish tropomyosin as an allergen due to its high homology with human tropomyosin.

Thicklip (Chelon labrosus) and flathead (Mugil cephalus) grey mullets fry production in Tunisian aquaculture

For several years Tunisia has opted to breed freshwater fish in reservoirs and artificial lakes, created for irrigation, as a strategy of providing high quality aquatic protein to the interior regions and providing work opportunities for local communities. The aim of this study was to summarize the main results accumulated by the last 20 year efforts made by the members of the National Institute for Marine Science and Technology (INSTM)-Aquaculture Laboratory to develop thicklip (Chelon labrosus) and flathead (Mugil cephalus) grey mullets fry production from captive broodstocks intended for stocking inland reservoirs (artificial lakes) and grow-out purposes Administration of human chorionic gonadotropin (hCG) at a priming dose of 10.000 IU kg−1 female bw, followed by 10.000 IU hCG and (100 or 200 μg kg−1 female bw of thicklip or flathead grey mullet respectively) as resolving dose resulted at the highest egg production for both species. Mean fecundity was 494.655 eggs kg-1 bw for thicklip grey mullet and 418.945 eggs kg-1 bw for flathead grey mullet. Fertilization rate of eggs produced was high (mean rate 83 % and 63 % for thicklip and flathead grey mullet respectively) and larvae hatched from those eggs at high rates (77 % and 88 %, respectively). The green method was more efficient than clear method to produce thicklip and flathead grey mullet fry, (i.e larvae had higher growth rate and better survival rates). The results of this study demonstrate the possibility to control reproduction and produce grey mullet fry in captivity. However, further research is needed to optimize the production protocol of eggs and fry of both grey mullet species.

Fish and tadpole composition as an indication of differences between micro-estuaries and micro-outlets in the Eastern Cape Province, South Africa

The fish and tadpole assemblages inhabiting micro-estuaries and micro-outlets along a warm-temperate section of the Eastern Cape coast were investigated over four seasons between 2015 and 2016. The specific aim of this study was to elucidate whether nekton assemblages in coastal microsystems are similar to those found in larger estuarine systems on the same coastline, and whether the presence or absence of tadpoles can indicate a difference between the two microsystem types. Oligohaline and/or freshwater conditions prevailed in micro-outlets for much of the sampling period, while micro-estuaries were mostly mesohaline. Nekton communities in micro-outlets were dominated by tadpoles (Xenopus laevis), with juvenile Pseudomyxus capensis sometimes present, while Oreochromis mossambicus, Gilchristella aestuaria, P. capensis and Mugil cephalus were the most common fish species in micro-estuaries which had an almost complete absence of tadpoles. The micro-estuaries had a low estuarine function when compared to temporarily open/closed estuaries, while the micro-outlets had very limited estuarine characteristics and an almost complete absence of fishes. Due to their restricted periods of stability and small size, micro-estuaries served as only intermediate nursery areas for small numbers of 0+ marine fish which, after less than a year, need to migrate to nearby larger estuarine systems that can provide the full range of nursery habitats for subsequent growth and development. The limited numbers of estuarine resident fishes (e.g. G. aestuaria) and freshwater fish species (e.g. O. mossambicus) confirm the marginal habitat and food availability in these microsystems for fishes that are normally abundant in other types of Eastern Cape estuaries and rivers. The results of this study confirm that there are clear distinctions between the nekton of the two microsystem types, thus making fish and tadpole assemblages a viable tool for differentiating between micro-estuaries and micro-outlets in this province.

A new perspective on biogeographic barrier in the flathead grey mullet (Pisces: Mugilidae) from the northwest Pacific.

The flathead grey mullet, Mugil cephalus has a global distribution in tropical, subtropical and temperate seas worldwide. Previous studies proposed that globally distributed M. cephalus comprises at least 14 different lineages, and divided into two or three groups in the northwest Pacific. Therefore, we hypothesized that there may exist at least two lineages in Korea. The aim of this study was to determine the number of lineages of flathead grey mullet in Korea, and detail their biogeographic boundaries, and taxonomic implications using various molecular markers. Two partial mitochondrial DNA (mtDNA) gene sequences (COI and 16S rRNA) and nine microsatellite loci were analyzed in 260 individuals from ten locations. Phylogenetic trees from two partial mtDNA gene sequences revealed two distinct lineages of flathead grey mullet (P distance= 0.016-0.021). Lineage 1 (L1) consisted of mullets from all locations except for the Pacific coasts of Japan, while lineage 2 (L2) consisted of mullets from the Jeju Island, Shanghai, and the Pacific coasts of Japan. The STRUCTURE analyses of msat data also revealed two distinct groups. This study was the first to reveal the coexistence of two lineages of flathead grey mullet in Korea. L2 was confined to the Jeju Island in Korea, implying a biogeographic boundary between the two lineages. The allopatric distribution and genetic heterogeneity between lineages may be affected by an ancient geographic isolation during the glacial period and maintained due to adaptation to oceanic characteristics. Collectively, the two lineages may be comprised of distinct species.

Microplastic pollution in surface water from east coastal areas of Guangdong, South China and preliminary study on microplastics biomonitoring using two marine fish

Microplastic pollution, one of the major global challenges, is a severe threaten to aquatic organisms. The purpose of this study was to investigate the abundance, distribution and characteristics of microplastics in coastal surface waters from eastern Guangdong, south China. We chose pelagic Konosirus punctatus and demersal Mugil cephalus from different sampling sites as candidate monitoring species for the ingestion of marine microplastics, and talked about the relationship between water samples and fish samples. We tried to find out the regulation about microplastics characteristics in fish samples and fish own traits. The mean abundance of microplastics in surface water was 8895 items/m3, small white fragments were dominating character. We need to increase the amount of fish data to further explore. This study would not only provide a detailed reference for a better understanding of microplastic pollution in Guangdong coastal areas, but also shed an insight in prospect of using fish as biomonitoring of microplastic wastes.

Growth pattern of three species of Mullets (Pisces: Mugilidae) in Sombreior River, Rivers State, Niger Delta, Nigeria

Length-weight relationships (LWRs) and condition factor are important biological information to assess the growth pattern and wellbeing of fish species influenced by numerous abiotic and biotic factors. To date, no data on the LWRs and condition of mullets in Sombreior River, Niger Delta. Hence, this research was conducted to determine abundance, length–weight relationship and Fulton’s condition factor (K) of three species of fish belonging to family Mugilidae in Sombreior River, Nigeria. There were a total of 248 samples from five sampling stations for a period of months. Fish species were of various sizes ranging from 24.66±0.40 to 26.35±0.26cm in length and 141.41±6.30 to 161.56±5.87g in weight. For the three species, slope (b) values ranged from 2.18 to 2.68 indicating a negative allometric growth of all fish species. The mean condition factor ranged from 0.89±0.03 forsix Mugil cephalus to 0.93±0.03 for Parachelon grandisquamis while the coefficients of determination (R2) of the LWR regressions ranged between 0.64 (Neochelon falcipinnis) and 0.79 (Parachelon grandisquamis). It was concluded that the mullets in the Sombreior River had a negative allometric growth pattern and the condition is showing the species were in good state of well-being since mean K values are greater than 1.

Effect of dietary supplementation of Chlorella vulgaris on several physiological parameters of grey mullet, Mugil cephalus.

The present paper aims to shed lights on effect of optimum dietary level of Chlorella vulgaris powder (CP) as a feed additive on some blood biochemical parameters (Cholesterol (CHO), triglyceride (TG), total protein (TP), glucose (GLU), glutamic oxaloacetic transaminase (GOT), glutamic pyruvic transaminase (GPT) and lysozyme) and digestive enzymatic activities (amylase, lipase and protease) of the grey mullet (Mugil cephalus L). Four experimental diets were supplemented with CP at 0, 5, 10 and 15 g kg−1diet (CP0, CP, CP10 and CP15). Number of twelve tanks (60-L) with three replicates for treatment group (n=10 per tank with average initial weights 14.95 ± 2.01 g) and the control group were considered. After 60 days of the feeding trial, fish fed CP5 diet had lower serum CHO and TG levels than did fish fed CP0, CP10 and CP15 diets (P 0.05). The highest serum total protein, amylase, protease, lipase and lysozyme activities were observed in fish fed CP5. Also, fish fed CP10 and CP15 diets had higher digestive enzymatic activities, serum total protein and lysozyme activities than did fish fed CP0 (P<0.05). These results indicate that dietary supplementation of 5 g chlorella powder in the commercial diets could improve the blood chemical responses and the activity of digestive enzyme in grey mullet.

Assessment of metal pollution impacts on Tilapia zillii and Mugil cephalus inhabiting Qaroun and Wadi El-Rayan lakes, Egypt, using integrated biomarkers.

Qaroun and Wadi El-Rayan lakes are exposed to a huge amount of discharges from different sources and numerous anthropogenic activities. Therefore, the present work aimed to evaluate the impacts of metal pollution on two wild fish species; Tilapia zillii and Mugil cephalus collected from lake Qaroun (eastern and western parts) and Wadi El-Rayan lakes (upper and lower lakes). Accumulation of metals (Cu, Zn, Cd, and Pb) in water, sediment, and five vital tissues as well as metal pollution index (MPI), contamination factor (CF), and pollution load index (PLI) were integrated as metal pollution biomarkers. Generally, these integrated endpoints had the same trend and indicated that the eastern part of lake Qaroun was the most polluted site followed by the lower lake of Wadi El-Rayan. To assess the environmental genotoxicity, the percentage DNA damage in different tissues of both fish species was estimated using the comet assay technique. The percentage of DNA damages showed tissue-, species- and site-specification. Hazard index (HI) has been used as an evaluation index for human health associated with fish consumption at the studied sites. This index showed that all metals were in the safe limits at normal consumption levels while adverse health effects are expected to occur at the subsistence consumption level. The safe HI for each metal at normal consumption level does not neglect that the combined cumulative risk impact of all metals is a sign of warning and the health of fish consumers nearby contaminated sites is threatened.

Structure and membership of gut microbial communities in multiple fish cryptic species under potential migratory effects

The animal gut microbiota evolves quickly towards a complex community and plays crucial roles in its host’s health and development. Factors such as host genetics and environmental changes are regarded as important for controlling the dynamics of animal gut microbiota. Migratory animals are an important group for studying how these factors influence gut microbiota because they experience strong environmental perturbations during migration. The commercially important grey mullet, Mugil cephalus, is a cosmopolitan species complex that display reproductive migration behaviour. There are three cryptic species of M. cephalus fish distributed across the Northwest Pacific, and their spawning sites overlap in the Taiwan Strait. This extraordinary natural occurrence makes the grey mullet an ideal model organism for exploring the nature of wild animal-gut microbiota relationships and interactions. This study investigates the diversity and structure of the gut microbial community in three cryptic M. cephalus species using 16S rRNA amplicon sequencing. Gut microbial compositions from adult and juvenile fish samples were analysed. Our results indicate that gut microbial communities within the grey mullet share a core microbiome dominated by Proteobacteria, Firmicutes and Actinobacteria. However, the structures of gut microbial communities were more distinct between adult mullet groups than they were between juvenile ones. Intriguingly, we found that adult fish that migrate to different geographical tracts harbour gut microbiota similar to historical records of seawater microflora, along their respective migration routes. This observation provides new insights into the interaction between aquatic animal gut microbial communities and the environments along their hosts’ migratory routes, and thus warrants future study.

Growth patterns and condition factor of fish live in Kuala Gigieng waters of Aceh Besar as the basic for sustainable fisheries development

Information on the growth pattern and condition factor is crucial for fisheries management. Hence, the objectives of the present study were to determine the growth patterns and condition factor of three fishes species dominated and harvested in Kuala Gigieng waters, Aceh Besar. The observation was carried out from April to May 2019, and the determination of sampling location was conducted using the random stratified sampling method, which was thought to represent Kuala Gigieng waters. There were three repetitions in each sampling location (station). Based on the results of the study, three dominant fishes species harvested in the Kuala Gigieng waters were belanak (Mugil cephalus), kerong-kerong (Terapon jarbua), and bolo-bolo (Atherinomorus lacunosus) as many as 48, 35, and 54 individuals, respectively. The growth pattern in all three fishes were negative allometric (b<3), which means that the increase in fish body length was faster than the fish body weight. The results also showed the correlation coefficient (r) ranged from 0.716 to 0.852. A high correlation coefficient indicated a close relationship between weight gain and length. The value of the condition factor of the three fishes based on the relative weight value (Wr) was above 100, meant that adequate food availability or low predator density and showed the condition of Kuala Gigieng waters was still in balance environmental condition. Generally, the condition of the Kuala Gigeng waters was relatively good and it could support fish growth as well.

Epizootics of epizootic ulcerative syndrome among estuarine fishes of Kerala, India, under post-flood conditions.

Epizootic ulcerative syndrome (EUS), primarily caused by the water mold Aphanomyces invadans, is an OIE-notifiable disease, having potential impacts on fisheries. We report EUS epizootics among estuarine fishes of Kerala, India, during 2018, under post-flood conditions 3 decades after its primary outbreak. Six fish species (Mugil cephalus, Platycephalus sp., Scatophagus argus, Arius sp., Planiliza macrolepis and Epinephelus malabaricus) were infected, including the first confirmed natural case in E. malabaricus and P. macrolepis. Salinity, surface temperature, dissolved oxygen and pH of resident water during the epizootic were <2 ppt, 25°C, 4.1 ppm and 7.0. The presence of zoonotic bacterial pathogens (Aeromonas veronii, Shewanella putrefaciens, Vibrio vulnificus and V. parahaemolyticus) in tissues of affected fish indicates that EUS-infected fish may pose a public health hazard if not handled properly. Lack of clinical evidence in the region during the last 3 decades, a high number of affected fishes, including 2 new fish species, the severity of skin lesions and very low water salinity (<2 ppt) during the outbreak in contrast to historical water salinity records suggest relatively recent invasion by A. invadans. Phylogenetic analysis based on the internal transcribed spacer region of the rRNA gene showed that the same clone of pathogen has spread across different continents regardless of fish species and ecotypes (fresh/estuarine environments). Altogether, the present study provides baseline data which can be applied in EUS management strategies within brackish-water ecosystems. We recommend strict surveillance and development of sound biosecurity measures against the disease.

Ontogeny of the digestive system and eye of reared flathead grey mullet, Mugil cephalus (Linnaeus, 1758), and evaluation of lipid deposition in the liver according to the feeding protocol

Ontogenic development of the digestive system and eye was studied in flathead grey mullet (Mugil cephalus) from hatching to the juvenile stage (69 days after hatching, dah), in rearing conditions. Moreover, the liver lipid content (area covered with lipid vacuoles, ACLV%) was evaluated according to the feeding protocol in association with the stomach content, using histological methods.Larval growth rate was slow until tail flexion was achieved (~14–15 dah), subsequently the growth was very rapid until reaching the mean total length ± SD of 22.27 ± 2.79 mm at the end of the rearing. The main structures of the digestive system were completely developed by 17 dah (395 degree days). Photopic vision began by 3 dah with the appearance of cones, while the ability for scotopic vision was acquired at 17 dah, when the larvae started gained the ability to see and catch prey in reduced light conditions.When the feeding protocol included both rotifers and Artemia nauplii, the mean ACLV remained high (15.66 ± 3.90%), as did the occurrence of lipid vacuoles in the intestine. ACLV in the liver started to decrease significantly during the weaning phase (until 40 dah, when it was 3.80 ± 2.51%). This was probably linked to the decreased total energy received by the larvae, because of the gradual reduction of the delivered Artemia coupled with the low acceptance of the artificial food. However, larvae accepted early artificial feed which was found in the stomach content a few days after the first administration. Consumption of growing amounts of artificial feed resulted in a growing ACLV, which rose again up to 20.38 ± 6.05% at 62 dah. The transition to a different artificial food (with half the lipid dose compared to the first one) led to a non-significant drop in ACLV in the liver, decreasing as much as 13.66 ± 7.19% on the last day of the rearing period.These results provide important information for the biology of this promising species for aquaculture, indicating that flathead grey mullet larvae rapidly develop the basic structures of the digestive and visual systems required to successfully overcome the most critical stage of commercial rearing. The study also confirms that histological evaluation of liver lipid content using the ACLV is a valuable tool in commercial aquaculture in order to identify the weaknesses of a feeding protocol and improve larval rearing protocols, and therefore production efficiency.

Fish Species Identification Using the Rhombic Squamation Pattern

The shape of fish scales is to a considerable degree species-specific, making it possible to identify species using only one scale per specimen. However, the shape of the rhombic lamination pattern has not been considered to identify species. This study used geometric morphometric statistical approaches to address two specific questions: (1) whether the rhombic lamination pattern of fish scales along the longitudinal axis varies within species and sex and (2) how many fish scales of the rhombic squamation pattern should be considered to obtain an adequate identification. These questions were assessed with Mancova and cross-validated quadratic discriminant analysis (DA) using the rhombus of one, three and six scales, and six, 14 and 26 landmarks, respectively, in order to discriminate between two co-generic species, Mugil cephalus and M. curema. The proportions of the total shape variance explained by the total length and the centroid size were 2.3, 11.8 and 10.5% and 4.2, 5.1 and 5.4% for 1, 3 and 6 scales, respectively. Analyses were carried out on the shape and the form (shape plus size). The Mancova and DA analyses were found to be effective in detecting differences in scale pattern shape between species (except in the case of 3 scales; p=0.079 for the shape and p=0.065 for the form), whereas no differences were recorded between size and sex in all cases. The findings indicate that a good identification of species is possible, with no significant differences when using shape or form. The discriminant analyses provided values of 75.8, 75.0 and 73.4% based on the shape, and of 72.7, 75.8 and 75.0% based on the form, for 1, 3 and 6 scales respectively. Thus, it is possible to obtain a rapid and reliable identification of species using the rhombus of one scale only without considering the size. This is a useful finding in practical terms since scaling requires data on length. In addition, the finding of a suitable discrimination using only the rhombus of one scale raises the possibility of using an ocular adaptor on a camera or mobile, allowing many individuals to be easily screened without having to collect scales.

Bioaccumulation of heavy metal lead (Pb) in different tissues of brackish water fish Mugil cephalus (Linnaeus, 1758)

Bioaccumulation of heavy metal lead (Pb) in different tissues of brackish water fish Mugil cephalus (Linnaeus, 1758)

Polybrominated diphenyl ethers (PBDEs) in surface water and fish tissues from Sundays and Swartkops Estuaries, Eastern Cape Province, South Africa: Levels, spatial distribution, seasonal variation and health implications

This study investigates the levels, composition profile and potential sources of polybrominated diphenyl ethers (PBDEs), in surface water and fish tissues from Sundays (SDE) and Swartkops Estuaries (SWE). The concentration of Ʃ ∑6PBDEs ranged from 2.5 to 39.1 ng/L for SDE and 2.5 to 168.8 ng/L for SWE. BDE-17, BDE-47, and BDE-100 were the predominant congeners in the sample matrices from both estuaries. In all the ten sampling sites studied, samples from the Motherwell Canal recorded the highest mean concentration as indicated by the hierarchical cluster analysis. Seasonal variations of the contaminants showed a high level of PBDEs in autumn for SDE, while for SWE samples collected in the summer recorded the highest concentration. The Ʃ ∑6PBDEs in muscles of twenty-two specimens of Mugil cephalus collected from SDE ranged from 1.3 to 9.1​ ng/g ww, while the concentration in twenty specimens of Pomadasys commersonnii from SWE ranged from 0.41 to 76.3 ng/g ww. The polybrominated diphenyl ethers (PBDEs) levels were higher in the gills of both fish species compared to their muscles. Hence, this study ascertains that the consumption of these fish species does not pose a non-cancer health risk. This paper suggests that long-term exposure and bioaccumulation of PBDEs as well as other organic contaminants should be investigated in various environmental matrices in other estuaries in South Africa.

The effects of two fish species mullet, Mugil cephalus, and tilapia, Oreochromis niloticus, in polyculture with white shrimp, Litopenaeus vannamei, on system performances: A comparative study

A comparative study was carried out to compare the effect of caging mullet and tilapia in a shrimp polyculture system. In six shrimp tanks (three tanks for each fish species), either mullet, Mugil cephalus (CCT-SM), or tilapia, Oreochromis niloticus (CCT-ST), was stocked in cages. In three other tanks, mullets were allowed to roam freely in shrimp tanks (D-SM). White shrimp, Litopenaeus vannamei (0.50 g), was cultured as the predominant species were distributed randomly into nine fibreglass tanks (5 m3) at a density of 300 shrimp/tank, while fish (1.50 g) were stocked at the same density of 10% of the initial total shrimp biomass. The results showed that water quality parameters were not significantly different among treatments (p > .05), except for total suspended solids (TSSs). System performances based on parameters such as total weight gain (2,808.15 g/tank) and nutrient recovery were higher in D-SM treatment (39.80% for nitrogen and 27.40% for phosphorus) than in CCT-SM and CCT-ST treatments (p < .05). These system performance parameters were significantly affected by the mullet-holding strategy; however, they were not affected by fish species. The addition of mullet or tilapia in shrimp tanks did not affect shrimp growth differentially. Fish growth performances based on parameters such as final weight (98.43 g/fish) and DGR (1.29 g/day) were significantly higher in D-SM treatment and were significantly different among D-SM, CCT-SM and CCT-ST treatments (p < .05). It is concluded that in shrimp–fish polyculture with a stocking density of fish at 10% of the initial total shrimp biomass, tilapia is more effective than mullet, when caged. However, under free-roaming conditions, the use of mullet is more effective in terms of system performances relative to a system holding caged tilapia.

The osteology of the golden grey mullet Liza aurata (Teleostei: Mugiliformes: Mugilidae) including interactive three-dimensional reconstructions.

Grey mullets are remarkably characterized by their overall uniform external morphology. Identifying species as well as positioning the Mugiliformes in a phylogenetic context is rather difficult. Most recently they were placed in the newly erected Ovalentaria, but more detailed relationships to potential sister taxa were not resolved. Studying the internal morphology, especially the osteology, might provide new insights into the evolution of the Mugiliformes as well as help clarify their phylogenetic position within the Ovalentaria. A detailed osteology of the golden grey mullet Liza aurata is presented. The use of cleared and stained specimens allowed for a complete examination of bony and cartilaginous structures, and a 3D reconstruction from a μCT data set provided additional information on the positional relationships of the bones. Following this, the data obtained were compared with different mugilid species, particularly with the flathead grey mullet Mugil cephalus. Several differences between these species could be identified, such as the position of the basisphenoid, the shape of the hyomandibular and the composition of the branchial arches. These characters might help in understanding the evolutionary changes happening within the mugiliforms and will provide the basis to study this taxon in detail, finally allowing the reconstruction of the body plan of grey mullets.

Distribution and risk assessment of some heavy metals in surface water, sediment and grey mullet (Mugil cephalus) from contaminated creek in Woji, southern Nigeria

The human health risk assessment associated with accumulation of nickel (Ni), cadmium (Cd), chromium (Cr), lead (Pb) and copper (Cu) in the tissues (gills, livers and muscles) of grey mullet (Mugil cephalus) collected from the creek in the Niger Delta region of Nigeria was investigated. Surface water, sediment and fish samples were collected and analysed from June to September 2019; estimated daily intake (EDI), target hazard quotient (THQ) and hazard index (HI) were determined. The mean concentration (mg/kg ww) of the tested metals followed the sequence: Cu (33.48 ± 15.54) > Cd (24.62 ± 12.11) > Pb (10.59 ± 9.12) > Cr (0.43 ± 0.66); while Ni was not detected in the sampled tissues. The HI for male and female (adults) are 7.612 and 7.840 respectively, while male and female (children) are 9.567 and 10.842 respectively.