Search Results (17)

Ammonia is widely regarded as the primary chemical pollutant responsible for fish toxicity in aquaculture. Scatophagus argus is an economically important euryhaline species extensively cultured in marine aquaculture. To investigate its physiological responses and molecular mechanisms under ammonia exposure, we determined the 96 h median lethal concentration (LC₅₀-96 h) of total ammonia nitrogen (TAN) for S. argus juveniles. Histopathological analyses were conducted at TAN concentrations of 0 (control), 30, and 60 mg/L, with transcriptomic analysis performed at 0 and 60 mg/L. The results showed that the LC₅₀-96 h for S. argus was 59.43 mg/L. Histological analysis revealed lamellar epithelial detachment and hepatocyte vacuolization in S. argus exposed to 60 mg/L TAN, indicating substantial structural impairment under ammonia stress. Transcriptomic profiling identified 245 differentially expressed genes (DEGs), comprising 142 upregulated and 103 downregulated genes. KEGG enrichment analysis indicated that DEGs were primarily enriched in energy metabolism and immune-related pathways. Key genes involved in glucose metabolism, amino acid metabolism, and cellular regulation (e.g., PFKM, PGM1, MAT2A, DDIT4) were significantly upregulated in energy metabolism pathways. In immune-related pathways, immune regulatory genes such as GIMAP4 and ARRDC3 were upregulated, while NAMLAA, associated with inflammatory modulation, was downregulated. Collectively, these transcriptional changes suggest that S. argus responds to external ammonia stress through coordinated regulation of energy metabolism and immune function. This study provides novel insights into the physiological and molecular strategies employed by S. argus in response to ammonia toxicity, offering a reference for environmental risk assessment and aquaculture management. Full article

The Scatophagus argus (S. argus) is a valuable aquaculture species in southern China, with females exhibiting significantly faster growth rates than males. However, the limited understanding of its sex determination and differentiation mechanisms poses challenges for sex-controlled breeding. MicroRNAs (miRNAs), key post-transcriptional regulators, are known to modulate critical pathways governing sex determination and differentiation across several vertebrates. However, there is currently no research on miRNAs related to sex determination and differentiation in S. argus. In this study, we analyzed the expression profiles of miRNA and mRNA in the gonads of adult S. argus using high-throughput sequencing. Our analysis identified 2210 miRNAs, including 482 differentially expressed miRNAs (DEMs) between sexes. These DEMs targeted 3340 differentially expressed genes (DEGs), generating 13,773 regulatory interaction pairs. The expression of some DEGs related to sex determination and differentiation was found to be either positively or negatively correlated with expression of DEMs that might regulate them. The novel_miR_110/Foxl2, novel_miR_802/Gdf9, and novel_miR_1263/Gdf9 show opposing differential expression trends, whereas sar-miR-143-5p-4/Gsdf, sar-miR-143-5p-5/Gsdf, and novel_miR_379/Sox3 show consistent trends. The regulatory relationship between miRNA and gene in the gonads does not seem to be conserved among different fish species. This work advances our understanding of the molecular mechanisms underlying the sexual dimorphism of gonadal gene expression in S. argus. The identified miRNA–gene interactions may serve as potential targets for future sex-control strategies, contributing to advancements in aquaculture practices for this species. Full article

The impact of dietary lipid sources on nutrient metabolism and reproductive development is a critical focus in aquaculture broodstock nutrition. Previous studies have demonstrated that fish oil supplementation modulates the expression of genes involved in steroid hormone synthesis, glucose, and lipid metabolism promoting ovarian development in female Scatophagus argus (spotted scat). However, the effects of fish oil on hepatic function at the protein level remain poorly characterized. In this study, female S. argus were fed diets containing 8% fish oil (FO, experimental group) or 8% soybean oil (SO, control group) for 60 days. Comparative proteomic analysis of liver tissue identified significant differential protein expression between groups. The FO group exhibited upregulation of lipid metabolism-related proteins, including COMM domain-containing protein 1 (Commd1), tetraspanin 8 (Tspan8), myoglobin (Mb), transmembrane protein 41B (Tmem41b), stromal cell-derived factor 2-like protein 1 (Sdf2l1), and peroxisomal biogenesis factor 5 (Pex5). Additionally, glucose metabolism-associated proteins, such as Sdf2l1 and non-POU domain-containing octamer-binding protein (Nono), were elevated in the FO group. Moreover, proteins linked to inflammation and antioxidant responses, including G protein-coupled receptor 108 (Gpr108), protein tyrosine phosphatase non-receptor type 2 (Ptpn2), Pex5, p120 catenin (Ctnnd1), tripartite motif-containing protein 16 (Trim16), and aquaporin 11 (Aqp11), were elevated in the FO group, while proteins involved in oxidative stress, such as reactive oxygen species modulator 1 (Romo1), cathepsin A (Ctsa), and Cullin 4A (Cul4a), were downregulated. These proteomic findings align with prior transcriptomic data, indicating that dietary fish oil enhances hepatic lipid metabolism, mitigates oxidative stress, and strengthens antioxidant capacity. Furthermore, these hepatic adaptations may synergistically support ovarian maturation in S. argus. This study provides novel proteomic-level evidence supporting the role of fish oil in modulating hepatic lipid and energy metabolism, thereby elucidating the role of fish oil in optimizing hepatic energy metabolism and redox homeostasis to influence reproductive processes, advancing our understanding of n-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFA) in teleost liver physiology. Full article

Vitellogenins (Vtgs) are key yolk precursor proteins in fish, serving as critical indicators of gonadal maturation in females and reliable biomarkers for detecting xeno-oestrogenic pollution, particularly through their expression in juveniles or males. The vtg gene family comprises multiple subtypes that are species-specific, necessitating precise characterisation and quantification for effective use as biomarkers in studies on estrogenic endocrine-disrupting chemicals (EEDCs). In this study, we successfully cloned and characterised the full-length cDNAs of three vtg subtypes (vtgAa, vtgAb, and vtgC) from Scatophagus argus. Differential expression analysis revealed that vtgAb exhibited the highest responsiveness to 17α-ethynylestradiol (EE2) exposure, with a 3-fold increase in vivo at 10.0 μg/g EE2 and a 30-fold increase in vitro at 10⁻⁷ mol/L EE2. The expression patterns were dose- and time-dependent, with peak expression observed 72 h post-exposure. While in vivo assays indicated moderate upregulation, in vitro experiments demonstrated significantly higher expression, attributed to direct hepatocyte interaction with EE2. These findings confirm vtgAb as the most responsive subtype to oestrogen exposure in S. argus and highlight the species’ tolerance to EE2, as compared to more sensitive species like Danio rerio. This study shows the evolutionary conservation of vtg transcripts across teleost species and reinforces the importance of subtype-specific characterisation to advance their application as biomarkers for EEDCs, with significant implications for environmental monitoring and pollution regulation. Full article

The vasa gene, encoding an ATP-dependent RNA helicase, and the nanos-2 gene, an RNA-binding protein, are essential for germ cell origination, migration, maintenance, and development in vertebrates and invertebrates. The expression levels of the vasa and nanos-2 genes have not yet been investigated or reported in crappie species. These two genes were partially sequenced and characterized, and their expression patterns were analyzed using reverse-transcription quantitative polymerase chain reaction (RT-qPCR) according to age and sex. The vasa sequences of white crappie (WC) females and males showed significant similarity with the vasa homologs of largemouth bass (Micropterus salmoides; 93.1–93.98%) and smallmouth bass (M. dolomieu; 91.95–92.77%), indicating its conserved nature within the Family Centrarchidae. The vasa sequence of black crappie (BC) females showed significant similarity with the vasa homologs of white crappie (91.67%), largemouth bass (96.10%), smallmouth bass (96.10%), spotted scat (Scatophagus argus; 97.37%), mandarin fish (Siniperca chutasi; 96.15%), Japanese sea bass (Lateolabrax japonicus; 94.87%), lumpfish (Cyclopterus lumpus; 91.95%), southern bluefin tuna (Thunnus maccoyii; 94.74%), large yellow croaker (Larimichthys crocea; 92.21%), and Nile tilapia (Oreochromis niloticus; 92.21%). The nanos-2 sequences of WC females, WC males, and BC females showed significant similarity with the nanos-2 of largemouth bass (92.92–96.36%), smallmouth bass (92.92–96.36%), and mandarin fish (92.66–94.34%). The expression of vasa in BC females was significantly higher at age-2 than at age-1, while WC males and females presented no significant age-related differences. Neither species had a significant difference in nanos-2 gene expression with age. The expression levels of vasa and nanos-2 were significantly higher in WC males than females. Full article

The spotted scat (Scatophagus argus) is an important ornamental species with sexually biased ornamental values that favor males. Therefore, it makes sense to breed mono-male fingerlings as ornamental fish. The spotted scat has an XX/XY sex determination system; therefore, the first step in producing genetically all-male offspring should be the induction of a fertile sex-reversed XY pseudo-female, which would then be mated with a normal XY male to produce a YY super-male. However, the XY pseudo-female produced by estradiol (E₂) treatment failed due to ovarian malformations. Here, male to female sex reversal was induced in spotted scat through a combination of E₂ and an androgen inhibitor (trilostane, TR). Spotted scat fingerlings of approximately 2.8–3.5 cm were fed a diet containing both E₂ (300 µg/g) and TR (300 µg/g). The fish were treated for 90 days and then fed a normal diet until they reached one year of age, when they were sampled. Twenty-eight treated XY individuals were identified using sex-linked markers. According to their gonadal histological characteristics, these treated XY fish could be divided into three groups: males with testes (n = 21), intersex individuals with ovaries–testes (n = 3), and fully sex-reversed individuals with ovaries (n = 4). All treated XX fish (n = 8) developed into normal females. There were no obvious abnormalities in the ovaries of the XY sex-reversed fish compared to the treated XX fish. Serum 11-ketotestosterone (11-KT) levels were significantly lower in XY-reversed females and treated XX females than in XY males. Compared with XY male fish, the expression of female (42sp50, foxl2, figla, zar1, and zp2) and male (dmrt1, gsdf, amh and cyp11b2) biased genes was up- and down-regulated, respectively, in the gonads of XY-completely sex-reversed fish. Immunohistochemical results indicate that 42Sp50 was expressed in oocytes of XY-partially and completely sex-reversed fish, while strong Gsdf signals were mainly detectable in testicular somatic cells of XY-partially sex-reversed fish and XY male fish. XY females were successfully produced by the combined treatment of E₂ and TR in the spotted scat. Their fertility will be tested in the future. Full article

Red coloration is considered an economically important trait in some fish species, including spotted scat, a marine aquaculture fish. Erythrophores are gradually covered by melanophores from the embryonic stage. Despite studies of black spot formation and melanophore coloration in the species, little is known about erythrophore development, which is responsible for red coloration. 1-phenyl 2-thiourea (PTU) is a tyrosinase inhibitor commonly used to inhibit melanogenesis and contribute to the visualization of embryonic development. In this study, spotted scat embryos were treated with 0.003% PTU from 0 to 72 h post fertilization (hpf) to inhibit melanin. Erythrophores were clearly observed during the embryonic stage from 14 to 72 hpf, showing an initial increase (14 to 36 hpf), followed by a gradual decrease (36 to 72 hpf). The number and size of erythrophores at 36 hpf were larger than those at 24 and 72 hpf. At 36 hpf, LC–MS and absorbance spectrophotometry revealed that the carotenoid content was eight times higher than the pteridine content, and β-carotene and lutein were the main pigments related to red coloration in spotted scat larvae. Compared with their expression in the normal hatching group, rlbp1b, rbp1.1, and rpe65a related to retinol metabolism and soat2 and apoa1 related to steroid hormone biosynthesis and steroid biosynthesis were significantly up-regulated in the PTU group, and rh2 associated with phototransduction was significantly down-regulated. By qRT-PCR, the expression levels of genes involved in carotenoid metabolism (scarb1, plin6, plin2, apoda, bco1, and rep65a), pteridine synthesis (gch2), and chromatophore differentiation (slc2a15b and csf1ra) were significantly higher at 36 hpf than at 24 hpf and 72 hpf, except for bco1. These gene expression profiles were consistent with the developmental changes of erythrophores. These findings provide insights into pigment cell differentiation and gene function in the regulation of red coloration and contribute to selective breeding programs for ornamental aquatic animals. Full article

Spotted scat (Scatophagus argus) can tolerate a wide range of salinity fluctuations. It is a good model for studying environmental salinity adaptation. Lipid metabolism plays an important role in salinity adaptation in fish. To elucidate the mechanism of lipid metabolism in the osmoregulation, the liver transcriptome was analyzed after 22 d culture with a salinity of 5 ppt (Low-salinity group: LS), 25 ppt (Control group: Ctrl), and 35 ppt (High-salinity group: HS) water by using RNA sequencing (RNA-seq) in spotted scat. RNA-seq analysis showed that 1276 and 2768 differentially expressed genes (DEGs) were identified in the LS vs. Ctrl and HS vs. Ctrl, respectively. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that the pathways of steroid hormone biosynthesis, steroid biosynthesis, glycerophospholipid metabolism, glycerolipid metabolism, and lipid metabolism were significantly enriched in the LS vs. Ctrl. The genes of steroid biosynthesis (sqle, dhcr7, and cyp51a1), steroid hormone biosynthesis (ugt2a1, ugt2a2, ugt2b20, and ugt2b31), and glycerophospholipid metabolism (cept1, pla2g4a, and ptdss2) were significantly down-regulated in the LS vs. Ctrl. The pathways related to lipid metabolisms, such as fatty acid metabolism, fatty acid biosynthesis, peroxisome proliferator-activated receptor (PPAR) signaling pathway, adipocytokine signaling pathway, fatty acid degradation, and unsaturated fatty acid biosynthesis, were significantly enriched in the HS vs. Ctrl. The genes of unsaturated fatty acid biosynthesis (scd1, hacd3, fads2, pecr, and elovl1) and adipocytokine signaling pathway (g6pc1, socs1, socs3, adipor2, pck1, and pparα) were significantly up-regulated in the HS vs. Ctrl. These results suggest that the difference in liver lipid metabolism is important to adapt to low- and high-salinity stress in spotted scat, which clarifies the molecular regulatory mechanisms of salinity adaptation in euryhaline fish. Full article

The spotted scat (Scatophagus argus) is the most widely commercially cultured fish in eastern and southern Asia that possess potential economic value. However, up to date, there are no studies reported on the selection of suitable reference genes in this fish, which is crucial for guaranteeing accurate and reliable results in RT-qPCR analyses. This study aimed at screening the most stable reference genes in the ovary and pituitary at different ovarian stages, which is of great significance for further research on the reproductive regulation mechanism of female S. argus. In this study, we selected twenty-one genes as the candidate reference genes, including four genes in the ovary (EEF1A, ACTB, B2M, and HPRT1), and seventeen genes in the pituitary (B2M, APOA1, CGBA, RPLP0, GNRHR, GUSB, TBP, SLC25A5, RPL4, PLA1A, GAPDH, GNB2L1, CTFS, HPRT1, RPS2, TFRC, and TUBB4B). To analyze the stability of the potential reference genes, we first used four commonly used software, BestKeeper, GeNorm, NormFinder, and ΔCt, and then we established comprehensive rankings with ReFinder. The results indicate that RPL4 and GNB2L1, and EEF1A and HPRT1 were the most appropriate reference genes for the pituitary and ovary of S. argus, respectively, in the three developmental stages of the ovary. Additionally, GeNorm analysis suggested that for the accurate normalization of gene expression, two reference genes were reliable in the ovary and pituitary of S. argus. To the best of our knowledge and understanding, this is the first study to identify appropriate reference genes for analyzing gene expression in S. argus. Consequently, this study can be used as a foundation for future research on the reproduction of S. argus. Full article

The growth performance of Scatophagus argus (25.53 ± 0.89 g) reared in Songkhla Lake, a brackish lagoon, was evaluated after feeding isonitrogenous and isocaloric diets containing hot-water extract from a seaweed, Sargassum sp., at 0, 0.25, 0.50, 0.75 or 1 g·kg⁻¹. Triplicate groups of fish were reared in 15 net cages (50 × 50 × 60 cm) at a density of 20 fish per cage, and the diets were fed twice a day at a rate of 5% of fish body weight per day for 8 weeks. The final body weight, weight gain (WG), average daily gain, and feed intake (FI) showed significant positive and quadratic responses to the Sargassum extract level. The highest WG (57.97%) and FI (0.34) were recorded in the fish that received the hot-water extract at 0.25–0.5 g·kg⁻¹ of diet. The protein efficiency ratio showed significant positive linear and quadratic responses to the Sargassum extract level, while the hepatosomatic index showed a significant positive linear response to the Sargassum extract level. The body protein and ash contents showed positive, linear and quadratic responses to the Sargassum extract level, and the highest crude protein (49%) was observed in the 0.5 g·kg⁻¹ diet group. There were no significant effects of the Sargassum extract levels on feed conversion ratio, food conversion efficiency, lipid and moisture contents, survival rate, hematocrit, and white or red blood cell counts. However, hematological data between fish in the control group and the Sargassum extract groups tended to be different. Overall, the optimum level of seaweed-extract supplementation for spotted scat under natural conditions was determined to be approximately 0.5 g·kg⁻¹ diet. Full article

Neuropeptide Y (Npy) is an intricate neuropeptide regulating numerous physiological processes. It is a highly conserved peptide known to improve feed intake in many vertebrates, including fishes. To enlighten the mechanism of Npy in spotted scat feed intake control, we cloned and identified the Npy cDNA sequence. We further examined its expression in some tissues and explored its expression effects at different time frames (hours and days). Here, we discovered that spotted scat Npy comprised a 300 bp open reading frame (ORF) and a 99 amino acid sequence. Npy was identified to be expressed in all tissues examined. Using in situ hybridization examination, we proved that npy has a wide expression in the brain of the spotted scat. Furthermore, the expression of npy in the hypothalamus significantly increased one hour after feeding (p < 0.05). Further, it was revealed that npy expression significantly increased in fish that were fasted for up to 5 days and significantly increased after refeeding from the 8th to the 10th day. This suggests that Npy is an orexigenic peptide, and hence, it increases food intake and growth in the spotted scat. Additionally, results from in vitro and in vivo experiments revealed that Npy locally interacts with other appetite-regulating peptides in the spotted scat hypothalamus. This research aimed to set a fundamental study in developing the feed intake regulation, improving growth and reproduction, which is significant to the aquaculture industry of the spotted scat. Full article

Unlike mammals and birds, many fishes have young sex chromosomes, providing excellent models to study sex chromosome differentiation at early stages. Previous studies showed that spotted scat possesses an XX-XY sex determination system. The X has a complete Dmrt3 copy (termed normal) and a truncated copy of Dmrt1 (called Dmrt1b), while the Y has the opposite (normal Dmrt1, which is male-specific, and a truncated Dmrt3 called Dmrt3△-Y). Dmrt1 is the candidate sex determination gene, while the differentiation of other sex-linked genes remains unknown. The spotted scat has proven to be a good model to study the evolution of sex chromosomes in vertebrates. Herein, we sequenced a neighbor gene of this family, Dmrt2, positioned farther from Dmrt1 and closer to Dmrt3 in the spotted scat, and analyzed its sequence variation and expression profiles. The physical locations of the three genes span across an estimated size of >40 kb. The open reading frames of Dmrt2a and its paralog Dmrt2b are 1578 bp and 1311 bp, encoding peptides of 525 and 436 amino acid residues, respectively. Dmrt2a is positioned close to Dmrt3 but farther from Dmrt1 on the same chromosome, while Dmrt2b is not. Sequence analysis revealed several mutations; insertions, and deletions (indels) on Dmrt2a non-coding regions and single-nucleotide polymorphisms (SNPs) on the Dmrt2a transcript. These indels and SNPs are sex-linked and showed high male heterogeneity but do not affect gene translation. The markers designed to span the mutation sites tested on four different populations showed varied concordance with the genetic sexes. Dmrt2a is transcribed solely in the gonads and gills, while Dmrt2b exists in the gonads, hypothalamus, gills, heart, and spleen. The Dmrt2a and Dmrt2b transcripts are profoundly expressed in the male gonads. Analyses of the transcriptome data from five other fish species (Hainan medaka (Oryzias curvinotus), silver sillago (Sillago sihama), Nile tilapia (Oreochromis niloticus), Hong Kong catfish (Clarias fuscus), and spot-fin porcupine fish (Diodon hystrix)) revealed testes-biased expression of Dmrt1 in all, similar to spotted scat. Additionally, the expression of Dmrt2a is higher in the testes than the ovaries in spotted scat and Hainan medaka. The Dmrt2a transcript was not altered in the coding regions as found in Dmrt1 and Dmrt3 in spotted scat. This could be due to the functional importance of Dmrt2a in development. Another possibility is that because Dmrt2a is positioned farther from Dmrt1 and the chromosome is still young, meaning it is only a matter of time before it differentiates. This study undeniably will aid in understanding the functional divergence of the sex-linked genes in fish. Full article

The spotted scat (Scatophagus argus) is an economically important cultured marine fish that exhibits a typical sexual size dimorphism (SSD). SSD has captivated considerable curiosity for farmed fish production; however, up till now the exact underlying mechanism remains largely unclear. As an important digestive and metabolic organ, the liver plays key roles in the regulation of fish growth. It is necessary to elucidate its significance as a downstream component of the hypothalamic-pituitary-liver axis in the formation of SSD. In this study, the liver physiological differences between the sexes were evaluated in S. argus, and the activity of several digestive and metabolic enzymes were affected by sex. Females had higher amylase, protease, and glucose-6-phosphate dehydrogenase activities, while males exhibited markedly higher hepatic lipase and antioxidant enzymes activities. A comparative transcriptomics was then performed to characterize the responsive genes. Illumina sequencing generated 272.6 million clean reads, which were assembled into 79,115 unigenes. A total of 259 differentially expressed genes were identified and a few growth-controlling genes such as igf1 and igfbp1 exhibited female-biased expression. Further analyses showed that several GO terms and pathways associated with metabolic process, particularly lipid and energy metabolisms, were significantly enriched. The male liver showed a more active mitochondrial energy metabolism, implicating an increased energy expenditure associated with reproduction. Collectively, the female-biased growth dimorphism of S. argus may be partially attributed to sexually dimorphic metabolism in the liver. These findings would facilitate further understanding of the nature of SSD in teleost fish. Full article

Spotted scat (Scatophagus argus) is an economically important marine aquaculture and ornamental fish species in Asia, especially in southeast China. In this study, skin transcriptomes of S. argus were obtained for three types of skin, including black-spotted skin (A), non-spotted skin (B) and caudal fin (C). A total of nine complementary DNA (cDNA) libraries were obtained by Illumina sequencing. Bioinformatics analysis revealed that 1358, 2086 and 487 genes were differentially expressed between A and B, A and C, and B and C, respectively. The results revealed that there were 134 common significantly differentially expressed genes (DEGs) and several key genes related to pigment synthesis and pigmentation, including tyrp1, mitf, pmel, slc7a2, tjp1, hsp70 and mart-1. Of these, some DEGs were associated with pigmentation-related Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, such as tyrosine metabolism, melanogenesis, the Wnt signaling pathway and the mitogen-activated protein kinase (MAPK) signaling pathway. The results will facilitate understanding the molecular mechanisms of skin pigmentation differentiation in S. argus and provide valuable information for skin coloration, especially the formation of spotted patterns on other marine fish species. Full article

From a total of 4140 marine fishes examined, eight species of parasitic isopods were reported from marine fishes in the Gulf of Thailand. These isopods were identified in two families, Corallanidae (Argathona macronema and Argathona rhinoceros) and Cymothoidae (Cymothoa eremita, Cymothoa elegans, Smenispa irregularis, Nerocila sundaica, Norileca indica and Norileca triangulata). Most of these parasitic isopods were found in the buccal cavity of their fish hosts with one host recorded as follows: C. eremita was found from Nemipterus hexodon, C. elegans was found from Scatophagus argus, N. sundaica was found from Saurida tumbil. The majority of the isopod specimens recorded in this study was S. irregularis, which was found in the buccal cavities of five host fish, Pampus argentius, Alepes melanoptera, Caranx hippos, Parastromateus niger and Terapon jarbua, with a prevalence of 11.67%, 10.43%, 9.78%, 6.10% and 4.21%, respectively. Argathona rhinoceros was found in the nasal cavity and branchial cavity of Epinephelus coioides, whereas A. macronema and N. triangulata were found on the skin of Epinephelus coioides and Seriolina nigrofasciata, respectively. The highest species diversity was found in E. coioides, which harbored two species of parasitic isopods, A. macronema and A. rhinoceros. Cymothoa eremita, C. elegans, S. irregularis and N. triangulata were recorded for the first time in the Gulf of Thailand. The reported discovery of C. eremita, S. irregularis, N. sundaica and N. triangulata in their fish hosts were new recorded hosts. Moreover, A. macronema and N. triangulata were found for the first time in the central Indo-Pacific region. Full article