Journal of Applied Ichthyology

Body colors are an important trait for the survival and reproduction of animals. In this study, transcriptomes and related single nucleotide polymorphisms (SNPs) of black- and red-colored Plectropomus leopardus (Lacépède) were identified to investigate important molecules and SNP markers associated with body color formation. In the comparison of red- and black-colored groups, 489 differential expressed genes (DEGs) were detected and among them, 236 up- and 253 down-regulated genes were found in the red-colored group. Gene ontology (GO) analysis of DEGs showed that pigmentation associated terms including pigment granule, pigmentation, melanin metabolic process, tyrosine metabolic process, pigment metabolic process, and pigmentation cell differentiation were enriched. Kyoto encyclopedia of genes and genomes (KEGG) analysis of DEGs presented that melanin related pathways (tyrosine metabolism and melanogenesis) were enriched. Furthermore, lipid metabolism and immune-related metabolism were also enriched. A total of 1,048,575 SNPs were detected from the transcriptome, and among them, 627,172 SNPs were located in the gene region. A total of 1323 SNPs were identified as differential SNPs in the comparison of black- and red-colored groups and were located in 1127 genes. Among the 1127 genes, 20 genes were identified as DEGs and were comprised of 9 SNPs with a potential role in body color selective breeding in fish farming.

Twenty-nine native freshwater fish species belonging to the four orders and eight families were collected from the Hongshui River, which belongs to the upper reaches of the Pearl River, to analyze their length-weight relationships (LWRs). Twenty-nine freshwater native fish were sourced using cages (0.2 m in height, 0.25 m in width, and 8 m in length, with a mesh size of 5 mm) and triple gillnets (20–40 m long, 1–3 m high, and mesh size, 2−3 cm) between December 2021 and July 2022. For each freshwater fish, the total length (TL) and weight were measured to the nearest 1.0 mm and 0.1 g. All LWR parameters of the twenty-nine species were statistically significant . The length-weight relationships for the nine species were new to the FishBase and new maximum lengths were recorded for the twenty species. The LWR values provided for the first time will help to validate the accuracy and predictability of the Bayesian models for estimating the species-specific growth parameters of the data-poor species.

Acentrogobius virgatulus (Jordan & Snyder, 1901) is a small coastal species of goby found along the Western Pacific. It is commonly found in Maizuru bay along the muddy sediment between the intertidal zone and depths of 10 m. In June and July of 2022, two independent agonistic interactions between male A. virgatulus were observed and recorded during its spawning season. One interaction, lasting over 4 minutes, included certain aggressive behaviors such as jaw locking, mouth gaping, fin extensions, rapid color changes, and fast strikes to the head and body. Another interaction exhibited similar mouth gaping, fin extension, and rapid color changes but did not lead to further escalation. These behaviors coincide with those found in similar species and provides in situ evidence of these uncommon interactions. This is the first record of agonistic behavior by an Acentrogobius species. Accumulating findings such as these can contextualize intraspecific interactions, reveal differences across multiple species, and guide future experiments.

In this study, the length-weight relationships were determined for four fish species of the upper Yangtze River, Sichuan province, China. The fish were collected by drift net (mesh size: 4 cm × 4 cm) and ground bamboo cages (1 cm × 1 cm) from Yalong River, Laixi River, Pingtung River, and Baoxing River. Samples were collected from March 2017 to December 2022. According to the length-weight function equation (), r² values ranged from 0.960 to 0.991 and the b values of LWRs ranged from 2.916 (Megalobrama pellegrini) to 3.095 (Claea dabryi).

This study used gas chromatograph-mass spectrometer (GC-MS) to determine three kinds of halogenated organic pollutants (HOPs) in the edible muscles of nine fish species in the Laibin section of the Hongshui River of Xijiang River in the Pearl River system. The results showed that the sum of organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers (PBDEs) in fish muscle was 8.94∼43.32 ng/g ww, 1.22∼4.09 ng/g ww, and ND∼0.13 ng/g ww, respectively. Evaluation indicators include analysis of the composition of homologous compounds, residues in different diets and habitats, and estimated daily intake (EDI) calculations. The analysis of the composition characteristics of homologous compounds showed that endrin was the most dominant in OCPs; hexachlorobenzene was the most dominant in PCBs; and BDE 154 was the most dominant PBDEs. Calculations of the levels of the HOPs in fish of different diets and habitats showed that OCPs and PCBs had the highest residues in carnivorous fish, and PBDEs had the highest residues in herbivorous fish. The residual OCPs, PCBs, and PBDEs in demersal fishes were the most. The estimated daily intake (EDI) results showed that daily fish consumption in the Laibin section of the Hongshui River would not cause HOPs health risks to the local residents. However, there is still a need for continuous monitoring of HOPs to reduce pollutant emissions and prevent pollution conditions from arising.

The long rough dab (Hippoglossoides platessoides) is one of the most common bottom dwelling fish species in the Barents Sea with a limited commercial value, even though it is regularly caught as bycatch. Adult H. platessoides can be found in large numbers along the west coast of Svalbard, but nothing is known about the spawning area of this species or the distribution of their eggs and larvae within Svalbard fjords. Recent findings of H. platessoides eggs in Kongsfjorden indicate that a spawning population exists either within the fjord or on the west Spitsbergen shelf.