Transcripts of genes encoding reproductive neuroendocrine hormones and androgen receptor in the brain and testis of goldfish exposed to vinclozolin,flutamide, testosterone,and their combinations

Vinclozolin (VZ) is a pesticide that acts as an anti-androgen to impair reproduction in mammals. However, VZ-induced disruption of reproduction is largely unknown in fish. In the present study, we have established a combination exposure in which adult goldfish were exposed to VZ (30 and 100 μg/L), anti-androgen flutamide (Flu, 300 μg/L), and androgen testosterone (T, 1 μg/L) to better understand effects of VZ on reproductive endocrine system. mRNA levels of kisspeptin (kiss-1 and kiss-2) and its receptor (gpr54), salmon gonadotropin-releasing hormone (gnrh3) and androgen receptor (ar) in the mid-brain, and luteinizing hormone receptor (lhr) in the testis were analyzed and compared with those of control following 10 days of exposure. kiss-1 mRNA level was increased in goldfish exposed to 100 µg/L VZ and to Flu, while kiss-2 mRNA level was increased following exposure to Flu and to combinations of 30 µg/L VZ with Flu, 100 µg/L VZ with T, and Flu with T. gpr54 mRNA level was increased in goldfish exposed to Flu and to combination of 30 µg/L VZ with Flu and 100 µg/L VZ with T. gnrh3 mRNA level was increased in goldfish exposed to 100 µg/L VZ, to Flu, and to combinations of 30 µg/L VZ with Flu, 100 µg/L VZ with T, and Flu with T. The mid-brain ar mRNA level was increased in goldfish exposed to Flu and to combinations of 30 µg/L VZ with Flu, 100 µg/L VZ with T, and Flu with T. Testicular lhr mRNA level was increased in goldfish exposed to Flu and to combination of 30 µg/L VZ with Flu. These results suggest that VZ and Flu are capable of interfering with kisspeptin and GnRH systems to alter pituitary and testicular horonal functions in adult goldfish and the brain ar mediates VZ-induced disruption of androgen production.     

Molecular evolution of myoglobin in the Tibetan Plateau endemic schizothoracine fish (<Emphasis Type="Italic">Cyprinidae</Emphasis>, <Emphasis Type="Italic">Teleostei</Emphasis>) and tissue-specific expression changes under hypoxia

Myoglobin (Mb) is an oxygen-binding hemoprotein that was once thought to be exclusively expressed in oxidative myocytes of skeletal and cardiac muscle where it serves in oxygen storage and facilitates intracellular oxygen diffusion. In this study, we cloned the coding sequence of the Mb gene from four species, representing three groups, of the schizothoracine fish endemic to the Qinghai-Tibetan Plateau (QTP), then conducted molecular evolution analyses. We also investigated tissue expression patterns of Mb and the expression response to moderate and severe hypoxia at the mRNA and protein levels in a representative of the highly specialized schizothoracine fish species, Schizopygopsis pylzovi. Molecular evolution analyses showed that Mb from the highly specialized schizothoracine fish have undergone positive selection and one positively selected residue (81L) was identified, which is located in the F helix, close to or in contact with the heme. We present tentative evidence that the Mb duplication event occurred in the ancestor of the schizothoracine and Cyprininae fish (common carp and goldfish), and that the Mb2 paralog was subsequently lost in the schizothoracine fish. In S. pylzovi, Mb mRNA is expressed in various tissues with the exception of the intestine and gill, but all such tissues, including the liver, muscle, kidney, brain, eye, and skin, expressed very low levels of Mb mRNA (<?8.0%) relative to that of the heart. The trace levels of Mb expression in non-muscle tissues are perhaps the major reason why non-muscle Mb remained undiscovered for so long. The expression response of the Mb gene to hypoxia at the mRNA and protein levels was strikingly different in S. pylzovi compared to that found in the common carp, medaka, zebrafish, and goldfish, suggesting that the hypoxia response of Mb in fish may be species and tissue-specific. Notably, severe hypoxia induced significant expression of Mb at the mRNA and protein levels in the S. pylzovi heart, which suggests Mb has a major role in the supply of oxygen to the heart of Tibetan Plateau fish.     

Inhibitory neurotransmitter serotonin and excitatory neurotransmitter dopamine both decrease food intake in Chinese perch (<Emphasis Type="Italic">Siniperca chuatsi</Emphasis>)

Aminergic neurotransmitters play important roles in the regulation of food intake. However, their effects on feeding in fish have been less explored and still unclear. In the present study, the effects of serotonin (5-HT) and dopamine (DA) on food intake were evaluated through intraventricular (ICV) administration in Chinese perch (Siniperca chuatsi) and the mRNA expression levels of neuropeptide Y (NPY), agouti gene-related protein (AgRP), and pro-opiomelanocortin (POMC) were detected. At 1 h post-injection, 5-HT significantly decreased food intake in a dose-dependent manner. The mRNA expression of NPY and AgRP were significantly decreased (p < 0.05), whereas the mRNA expression of POMC was significantly increased (p < 0.05), suggesting the involvement of NPY, AgRP, and POMC in inhibitory action of 5-HT on food intake in Chinese perch. DA significantly decreased (p < 0.05) food intake and AgRP mRNA expression at 1 h post-injection, indicating the inhibitory effect of DA on food intake might be mediated through AgRP. This might shed new light on the regulation of food intake in Chinese perch.     

Impact of food type on growth,survival and reproduction of the cyclopoid copepod <Emphasis Type="Italic">Cyclopina kasignete</Emphasis> as a potential live food in aquaculture

This study compared the efficacy of different dietary algae on the growth and reproduction of the cyclopoid copepod Cyclopina kasignete, a potential live food species for fish larvae in aquaculture. The experimental diets for the copepod consisted of three monoalgal diets (Nannochloropsis oculata, Tisochrysis lutea and dry Melosira sp.) and two mixed algae diets (T. lutea?+?N. oculata, T. lutea?+?dry Melosira sp.). The experiment was carried out for 30 days, and the population growth, survival and reproductive performance (generation time, hatching rate, life spawning times, daily offspring production, eggs per sac, lifespan and sex ratio) were used to assess the responses of C. kasignete to different food types. Population growth, survival and reproductive capacities of C. kasignete were significantly affected by the mono and binary species of algal diets. The results showed that copepods exhibited superior growth, survival and productivity when fed on fresh T. lutea, dry Melosira sp. and a mixture of both species compared to other dietary treatments. Copepods produced comparable growth, survival and productivity when fed on diatoms (dry Melosira sp.) as a single or in combination with other algae. This study indicates that cyclopoid copepod C. kasignete grow fast and have the potential to serve as a live food for aquaculture. The algae T. lutea, dry Melosira sp. and their combination are appropriate food to sustain the growth and reproduction of this copepods in mass culture as a potential live food in fish hatchery.     

Aquaculture produces wholesome food: cultured fish as a valuable source of n-3 fatty acids

Long-chain unsaturated n-3 fatty acids are of remarkable significance in human nutrition. They have antiatherosclerotic efficacy and other beneficial health effects too. Aquaculture fish, e.g. cyprinids, such as silver carp (Hypophthalmichthys molitrix), bighead carp (Aristichthys nobilis), common carp (Cyprinus carpio), tench (Tinca tinca), and salmonids like Atlantic salmon (Salmo salar) and rainbow trout (Oncorhynchus mykiss) as well as European catfish (Silurus glanis), Baltic whitefish (Coregonus maraena), European seabass (Dicentrarchus labrax), gilthead seabream (Sparus aurata), and Nile tilapia (Oreochromis niloticus), are rich in these fatty acids. When fed on suitable diets, the fatty acid composition of cultured fish can be influenced advantageously. Several clinical tests proved the effectiveness of the consumption of farmed fish in promoting human health. Thus, aquaculture fish can be recommended as wholesome food.     

Activity of metabolic enzymes and muscle-specific gene expression in parr and smolts Atlantic salmon <Emphasis Type="Italic">Salmo salar</Emphasis> L. of different age groups

This study was conducted to characterize the energy metabolism level and the features of muscle growth regulation during the development of Atlantic salmon (Salmo salar) inhabiting the Indera River (Kola Peninsula, Russia). The activities of aerobic and anaerobic enzymes (cytochrome c oxidase and lactate dehydrogenase) and carbohydrate metabolism enzymes (glucose-6-phosphate dehydrogenase, glycerol-3-phosphate dehydrogenase, and aldolase) were measured in muscle and liver tissue. Gene expression levels of myosin heavy chain (MyHC), myostatin (MSTN-1a), and myogenic regulatory factors (MRFs—MyoD1a, MyoD1b, MyoD1c, Myf5, myogenin) were measured in the white muscles of salmon parr of ages 0+, 1+, 2+, and 3+ and smolts of ages 2+ and 3+. Multidirectional changes in the activity of enzymes involved in aerobic and anaerobic energy metabolism with age were shown in the white muscles of the parr. The cytochrome c oxidase activity was higher in muscles of underyearlings (0+) and yearlings (1+) and decreased in 2+ and 3+ age groups. The activity of lactate dehydrogenase, in contrast, increased with age. The patterns of changes in expression levels of MyoD1a, MyoD1b, myogenin, MyHC, and MSTN-1a at different ages of the parr were similar. Particularly, the expression of these genes peaked in the yearling parr (1+) and then decreased in elder groups. The differences were revealed in parameters studied between the parr and smolts. The level of aerobic and anaerobic metabolism enzyme activities was higher in the white muscles of smolts than in parr. The activity of carbohydrate metabolism enzymes was decreased in the smolts’ livers. The expression levels of MyHC, MyoD1a, MyoD1b, and myogenin were lower in smolts at age 2+ compared to parr. These findings expand our knowledge of age-related and stage-related features of energy metabolism and muscle development regulation in young Atlantic salmon in their natural habitat. The results might be used for monitoring of the salmon population during restoration and rearing.     

New insights into the evolution,hormonal regulation,and spatiotemporal expression profiles of genes involved in the Gfra1/Gdnf and Kit/Kitlg regulatory pathways in rainbow trout testis

The present study aimed to investigate whether the Gfra1/Gdnf and/or Kit/Kitlg regulatory pathways could be involved in the regulation of spermatogonial cell proliferation and/or differentiation in fish. Homologs of the mammalian gfra1, gdnf, kitr, and kitlg genes were identified in gnathostomes and reliable orthologous relationships were established using phylogenetic reconstructions and analyses of syntenic chromosomal fragments. Gene duplications and losses occurred specifically in teleost fish and members of the Salmoninae family including rainbow trout (Oncorhynchus mykiss) and Atlantic salmon (Salmo salar). Some duplicated genes exhibited distinct spatiotemporal expression profiles and were differently regulated by hormones in rainbow trout. Undifferentiated type A spermatogonia expressed higher levels of kitrb and kitra2 making them possible target cells for the gonadal kitlgb and somatic kitlga before the onset of spermatogenesis. Interestingly, gdnfa and gdnfb ohnologous genes were poorly expressed before the onset of spermatogenesis. The expression level of gdnfb was correlated with that of the vasa gene suggesting that the late increased abundance of gdnfb during spermatogenesis onset was due to the increased number of spermatogonial cells. gfra1a2 was expressed in undifferentiated type A spermatogonia whereas gfra1a1 was mainly detected in somatic cells. These observations indicate that the germinal gdnfb ligand could exert autocrine and paracrine functions on spermatogonia and on testicular somatic cells, respectively. Fsh and androgens inhibited gfra1a2 and gdnfb whereas gfra1a1 was stimulated by Fsh, androgens, and 17α, 20β progesterone. Finally, our data provide evidences that the molecular identity of the male germ stem cells changes during ontogenesis prior to spermatogenesis onset.     

Environmental factors on virulence of <Emphasis Type="Italic">Aeromonas hydrophila</Emphasis>

Aeromonas hydrophila are known for being opportunistic pathogens, harboring various virulence factors and triggering lesions and death in fish. The disease caused by bacteria can make fish inappropriate for human consumption, besides representing a risk to public health. The pathogenesis can be influenced by environmental variables, affecting fish productivity and mortality. The present study aimed to determine whether A. hydrophila harbor the virulence genes aerolysin, hydrolipase, elastase, lipase, cytotonic enterotoxin (ast), lateral flagellum (laf), and polar flagellum (fla) and to evaluate the influence of environmental variables on in vitro growth, in vivo virulence and expression of some of these genes. Polymerase chain reaction (PCR)-based screening for the presence of these virulence genes was performed on 35 isolates. Six isolates containing different profiles of virulence genes were tested for in vitro growth under different conditions of pH, temperature, and ammonia and for in vivo virulence under these same environmental conditions. RT-qPCR was used to quantify the expression of aerolysin, lipase, and fla genes. All the tested environmental factors influenced the growth of A. hydrophila, while pH and ammonia concentrations influenced the bacterial virulence. The expression of the fla gene increased when bacteria were grown in higher ammonia concentration. The mortality established by Aeromonas is influenced by several environmental factors pinpointing the importance of its control in fish farming to avoid higher economic loses associated to bacterial disease outbreaks.     

Development of a simple and rapid monoclonal antibody-based flow through immunogold assay (FIA) for detection of <Emphasis Type="Italic">Aeromonas hydrophila</Emphasis>

In this study, we developed a simple, low-cost, and rapid flow through immunogold assay (FIA) for detection of Aeromonas hydrophila in fish tissues and validated. The developed assay relied on colloidal gold conjugated highly specific monoclonal antibody (B8E3) against 20 kDa protein of A. hydrophila. The assay can be completed within 5 min including antigen (sample) preparation and exhibited no cross-reaction with other major aquatic pathogens such as Vibrio anguillarum, V. parahaemolyticus, V. harveyi, white spot syndrome virus (WSSV), and Aphanomyces invadans. A wider range of Aeromonas species were tested including A. caviae, A. dhakensis, A. sobria, A. veronii, A. culicicola, A. sharmana, and A. schubertii and no cross-reactivity could be observed. The developed technique FIA could detect 10³ CFU/ml of aeromonad cells. In addition, the FIA is as sensitive as the first-step polymerase chain reaction (PCR) and 1000 times sensitive than the immunodot blot method. The validation study revealed the accuracy of FIA by comparing with the standard first-step PCR. The proposed FIA is low-cost, easy-to-use, and compatible for field-level analysis of A. hydrophila in fish tissues. Our developed FIA could successfully detect A. hydrophila at early stage of the infection and could be easily availed by farmers, fish producers, non-technicians, and technicians in the aquaculture industry.     

Diethylstilbestrol arrested spermatogenesis and somatic growth in the juveniles of yellow catfish (<Emphasis Type="Italic">Pelteobagrus fulvidraco</Emphasis>), a fish with sexual dimorphic growth

In fish, spermatogenesis and somatic growth are mainly regulated by hypothalamic-pituitary-gonadal (HPG) and hypothalamic-pituitary-somatic (HPS) axes, respectively. Xenoestrogens have been reported to impair spermatogenesis in some fishes, and arrest somatic growth in some others, whereas, whether xenoestrogens are capable of disrupting spermatogenesis and somatic growth simultaneously in fish that exhibits sexual dimorphic growth is little known, and the underlying mechanisms remain poorly understood. In this study, male juveniles of yellow catfish (Pelteobagrus fulvidraco), which exhibits a sexual dimorphic growth that favors males, were exposed to diethylstilbestrol (DES) for 28 days. After exposure, DES significantly disrupted the spermatogenesis (decreased gonadal-somatic index (GSI) and germ cell number) and arrested the somatic growth (declined body weight) of the catfish juveniles. Gene expression and plasma steroid analyses demonstrated the suppressed mRNA levels of genes in HPG axis (gnrh-II, fshβ, and lhβ in the brain and dmrt1, sf1, fshr, cyp17a1, cyp19a1a, and cyp11b2 in the testis) and decreased 17β-estrodial (E2) and 11-ketotestosterone (11-KT) levels in plasma. Further analysis revealed the arrested germ cell proliferation (cyclin d1), meiosis (dmc1, sycp3), and enhanced apoptosis (decreased bcl-2 and elevated bax/bcl-2 ratio) in the testis. Besides, DES also suppressed the mRNA levels of genes in HPS axis (ghrh, gh, and prl in the brain and ghr, igf1, igf2a, and igf2b in the liver). The suppressed HPG and HPS axes were thus supposed to disturb spermatogenesis and arrest somatic growth in yellow catfish. The present study greatly extended our understanding on the mechanisms underlying the toxicity of DES on spermatogenesis and somatic growth of fish.     

Morphology,sex steroid level and gene expression analysis in gonadal sex reversal of triploid female (XXX) rainbow trout (<Emphasis Type="Italic">Oncorhynchus mykiss</Emphasis>)

In non-mammalian vertebrates, estrogens and expressions of cyp19a1 and foxl2 play critical roles in maintaining ovary differentiation and development, while dmrt1 and sox9 are male-specific genes in testicular differentiation and are highly conserved. In order to deeply understand the morphological change, sex steroids level and molecular mechanism of triploid female gonadal reversal in rainbow trout, we studied the ovary morphology, tendency of estradiol-17β (E2) and testosterone (T) levels and the relative expressions of dmrt1, cyp19a1, sox9 and foxl2 in juvenile and adult fish. Our results demonstrated that the development of triploid female gonads in rainbow trout went through arrested development, oocytes dedifferentiation, ovary reconstruction and sex reversal finally. During early gonadal development (154–334 days post-fertilization), the expressions of foxl2 and cyp19a1 increased linearly, while expressions of dmrt1 and sox9 were extremely suppressed, and E2 level was higher, while T level was lower. During the mid-to-late period of triploid female gonadal development (574–964 days post-fertilization), the expressions of dmrt1 and sox9 remained high and were very close to the quantity of diploid male genes, and T levels were even reaching diploid male plasma concentrations, while expressions of cyp19a1 and foxl2 were decreased, leading to decrease in E2 level. We realized that the development model of rainbow trout triploid female gonads was extremely rare, and the regulatory mechanism was very special. Genes involved in gonadal development and endogenous estrogens are pivotal factors in fish natural sex reversal.     

Immunomodulatory effects of <Emphasis Type="Italic">Rhodomyrtus tomentosa</Emphasis> leaf extract and its derivative compound,rhodomyrtone, on head kidney macrophages of rainbow trout (<Emphasis Type="Italic">Oncorhynchus mykiss</Emphasis>)

Rhodomyrtus tomentosa is a medicinal plant that shows biological effects including immunomodulatory activity on human and other mammals but not in fish. In this study, we evaluated the in vitro immunomodulatory effects of R. tomentosa leaf extract and its active compound, rhodomyrtone, on the immune responses, using rainbow trout (Oncorhynchus mykiss) head kidney (HK) macrophages as a model. The tested immune functions included the expression of genes involved in innate immune and inflammatory responses and the production of reactive oxygen species (ROS). Gene expression was evaluated after exposure to 10 μg mL^?1 of R. tomentosa and 1 μg mL^?1 of rhodomyrtone for 4 and 24 h. R. tomentosa and rhodomyrtone induced changes in the expression of pro-inflammatory cytokines (il1β, il8, and tnfα), anti-inflammatory cytokines (il10 and tgfβ), inducible enzymes (inos, cox2, and arginase), and an antioxidant enzyme (gpx1). Co-exposure of R. tomentosa with LPS resulted in a prominent reduction in the expression of genes related to an inflammatory process (il1β, il8, tnfα, inos, saa, hepcidin, and gpx1), suggesting anti-inflammatory effects. Similarly, co-exposure of rhodomyrtone with LPS led to a downregulation of inflammation-related genes (il1β, inos, saa, and hepcidin). In addition, exposure to both natural plant products caused a reduction in cellular ROS levels by HK macrophages. The present results indicate that R. tomentosa and rhodomyrtone exerted immunostimulatory and anti-inflammatory effects on fish macrophages, thus opening up the possibility of using these natural products to further develop immunostimulants for health management in aquaculture.     

Resveratrol supplementation improves lipid and glucose metabolism in high-fat diet-fed blunt snout bream

Here, we aimed to investigate whether resveratrol (RSV) can ameliorate high-fat diet (HFD)-induced metabolic disorder in fish. Blunt snout bream (Megalobrama amblycephala) with average weight 27.99 ± 0.56 g were fed a normal fat diet (NFD, 5% fat, w/w), a HFD (11% fat), or a HFD supplemented with 0.04, 0.36, or 1.08% RSV for 10 weeks. As expected, fish fed a HFD developed hepatic steatosis, as shown by elevated hepatic and plasma triglycerides, raised whole body fat, intraperitoneal fat ratio and hepatosomatic index, and increased plasma alanine aminotransferase (ALT) and aspartate aminotransferase (AST). RSV supplementation lessened increases in body mass, whole body fat, and intraperitoneal fat, and alleviated development of hepatic steatosis, elevations of plasma triglyceride and glucose, and abnormalities of ALT and AST in HFD-fed fish. RSV supplementation increased SIRT1 messenger RNA (mRNA) expression and consequently hepatic mRNA expression of adipose triglyceride lipase (ATGL), carnitine palmitoyltransferase (CPT1a), and microsomal triglyceride transfer protein (MTTP), implying upregulation of lipolysis, β-oxidation, and lipid transport, respectively, in the liver. Conversely, hepatic lipoprotein lipase (LPL), sterol regulatory element-binding protein 1 (SREBP-1c), peroxisome proliferator-activated receptor γ (PPARγ), and ATP citrate lyase (ACLY) mRNA expression were decreased, implying suppression of fatty acid uptake, lipogenesis, and fatty acid synthesis. Additionally, RSV downregulated glucokinase (GCK) and sodium-dependent glucose cotransporter 1 (SGLT1) and upregulated glucose transporter 2 (GLUT2) mRNA expression, thus restoring normal glucose fluxes. Thus, RSV improves lipid and glucose metabolisms in blunt snout bream, which are potentially mediated by activation of SIRT1.     

What can be expected of a T90 extension piece to improve selectivity in bottom trawl multispecific fisheries in the Bay of Biscay?

In the Bay of Biscay, the selective properties of otter trawls have mainly been studied with regard to single species. However, for bottom trawl multispecific fisheries targeting fish, it remains challenging to find a selective device capable of limiting catches of small individuals of several species without commercial losses. The present study focuses on an innovative technical solution to reduce catches of undersized individuals in a multispecies bottom trawl fishery in the Bay of Biscay. We tested a cylinder made of 100-mm diamond meshes turned at 90°, namely T90 inserted in the extension piece. We present the selectivity results obtained for six commercial species. This device allows the escape of small Solea solea, Trachurus trachurus and Spondyliosoma cantharus individuals. No commercial losses of Sepia officinalis were recorded. Patterns for Dicentrarchus labrax and Mullus surmuletus require further investigation due to limited fish size ranges in the dataset.     

Influence of different microalgal diets on gonadal development of the carpet shell clam <Emphasis Type="Italic">Ruditapes decussatus</Emphasis> broodstock

Studies considering broodstock conditioning of Ruditapes decussatus mostly used flagellates and diatoms for feeding, mainly Isochrysis galbana and Chaetoceros calcitrans, respectively. The present study evaluated the effect of different microalgal diets on gonadic maturation of R. decussatus including three microalgae species (C. calcitrans, Tetraselmis suecica, and Nannochloropsis oculata) which were used to prepare six diets: three monospecific and three bispecific mixed diets at a proportion of 1:1. Clams were daily fed at a ratio of 1% dry weight of algae/live weight of clam and unfed treatment was used as control. Results showed that clams fed C. calcitrans alone or mixed with T. suecica attained earlier full maturity with the highest response to spawning induction (after 34 conditioning days) and largest proportion in the partial spawning phase for both, followed by T. suecica alone after 48 days. In contrast, N. oculata alone or mixed diets demonstrated poor performance for gonadal maturation. Unfed treatment did not show any sign of maturation. The results indicated that T. suecica has high conditioning potential like C. calcitrans and their mixture gave the highest benefit. Therefore, T. suecica can be recommended for R. decussatus broodstock conditioning.     

Effect of <Emphasis Type="Italic">Lactococcus lactis</Emphasis> K-C2 on the growth performance,amino acid content and gut microflora of amberjack <Emphasis Type="Italic">Seriola dumerili</Emphasis>

This study aimed to evaluate the effect of Lactococcus lactis K-C2 on the growth performance, microbial diversity, and release of free amino acids in the intestinal tract and the edible parts of young amberjack, Seriola dumerili. Fish were fed a diet with or without strain K-C2 (2?×?10¹⁰ cfu/g feed) for 25 days. The results indicated that the growth performance of fish in the treated group was significantly higher than those in the control group (p?<?0.05). The amount of five amino acids (aspartate, sarcosine, taurine, alanine, and arginine) in the gut content and 13 of 21 amino acids in the edible parts of fish in the treated group were significantly higher (p?<?0.05) than those in the control group. Sphingomonas, Propionibacterium, and Mycobacterium were observed in gut microflora of fish in both the control and treated groups. Staphylococcus and Kocuria were detected in one sample from the control and treated groups; Acinetobacter and Acidobacteria were found in one sample from the control group. L. lactis was only found in one sample in the treated group. In conclusion, the dietary administration of probiotic L. lactis stimulated growth, reduced feed consumption, and improved the nutritional value of cultured amberjack.