The occurrence of antibiotics and potential health risk of 300 cultured fish samples from 19 provinces in China were investigated. The levels of 28 antibiotics (15 fluoroquinolones, 4 tetracyclines, 8 macrolides and rifampin) in 8 fish species were measured through liquid chromatography electrospray tandem mass spectrometry. As a result, 10 antibiotics were detected with an overall detection frequency of 24.3%, and the individual detection frequency of antibiotics ranged from 0.33 to 16.7%. The extremely high concentrations (above 100 µg/kg) of doxycycline and erythromycin were found in the samples. Antibiotics with high detection frequency was noticed in largemouth bass (41.2%), followed by snakehead (34.4%) and bream (31.2%). Specifically, Heilongjiang, Xinjiang, Qinghai and Gansu presented high detection frequency values of more than 60%. Moreover, the highest mean concentration was observed in Shandong, and the concentration covered from 34.8 µg/kg to 410 µg/kg. Despite the high detection frequency and levels of antibiotics were found in samples, ingestion of cultured fish was not significantly related to human health risks in China, according to the calculated estimated daily intakes and hazard quotients. These results provided us the actual levels of antibiotics in cultured fish and human health risk assessment of consuming fishery products.

Malachite green (MG) is a synthetic poisonous organic compound that has been banned in many countries as a veterinary drug for aquaculture. An efficient, fast and sensitive method is urgently needed for monitoring the illegal use of malachite green (MG) in aquaculture. In this study, a novel ratiometric fluorescence immunoassay was established. Nitrogen-doped carbon quantum dots were used as ratiometric fluorescent probes with a fluorescence peak at 450 nm. Horseradish peroxidase was employed to convert o-phenylenediamine to 2,3-diaminophenazine, with a new fluorescence peak at 580 nm and a strong absorption at 420 nm. The inner filter effect between N-CQD fluorescence and DAP absorption was identified. It allows for the ratiometric detection of MG using a fluorescent immunoassay. The results demonstrated a linear ratiometric fluorescence response for MG between 0.1 and 12.8 ng·mL⁻¹. The limit of detection of this method was verified to be 0.097 μg·kg⁻¹ with recoveries ranging from 81.88 to 108%, and the relative standard deviations were below 3%. Furthermore, this method exhibited acceptable consistency with the LC-MS/MS results when applied for MG screening in real samples. These results demonstrated a promising application of this novel ratiometric fluorescence immunoassay for MG screening with the merits of rapid detection, simple sample preparation, and stable signal readout. It can be an alternative to other traditional methods if there are difficulties in the availability of expensive instruments, and achieve comparable results or even more sensitivity than other reported methods.

Tetrodotoxin (TTX) was simultaneously detected in the fresh and heat-processed aquatic products by high-performance liquid chromatography–tandem mass spectrometry method. The detection conditions were investigated, including the chromatography column and mobile phase. Based on the optimized parameters, a sensitive determination method of TTX was established. The proposed method featured the merits of a good linear relationship between signal and TTX concentration (R² = 0.9998), a wide detection matrix-based range of 0.2–100 ng/g, and a low detection limit of 0.2 ng/g, etc. The spiked assays evidenced its accuracy and reliability with recoveries of 90.5–107.2%. Finally, the developed method was simultaneously successfully applied in the determination of TTX in various fresh and heat-processed aquatic products.

The intensive aquaculture strategy and recirculating aquaculture system often lead to the production of off-flavor compounds such as 2-methyl-isoborneol (2-MIB) and Geosmin (GSM). The regular purge and trap extraction followed by analysis with gas chromatography-mass spectrometry (GC-MS) usually involve a complicated assembly of facilities, more working space, long sample preparation time, and headspace solid-phase microextraction (SPME). In this work, a method with easier sample preparation, fewer and simplified facilities, and without SPME on GC-MS analysis is developed for the determination of 2-MIB and GSM in fish samples. Unlike previous methods, solvent extract from samples, QuEChERS-based cleanup, and solid-phase extraction for concentration are applied. The LOD (S/N>3) and LOQ (S/N>10) of this method were validated at 0.6μg/kg and 1.0μg/kg for both 2-MIB and GSM, which are under the sensory limit (1μg/kg). Application of this method for incurred fish samples demonstrated acceptable analytical performance. This method is suitable for large-scale determination of 2-MIB and GSM in fish samples, owing to the use of simple facility and easy-to-operate procedure, rapid sample preparation, and shorter time for GC-MS analysis without SPME.

The freshness of Atlantic salmon is influenced mainly by tissue metabolism, which in turn is affected by storage time and conditions. The alterations in taste profiles and nutritional values of salmon when packaged using vacuum methods have not been fully understood, and the factors contributing to these changes require further research. In this work, the extraction method for flavor nutrients from salmon was optimized via the Plackett–Burman (PB) test. A sensitive and rapid targeted metabolomics method for the simultaneous determination of 34 nutrients was successfully established via ultra-performance liquid chromatography–triple quadrupole/linear ion trap composite mass spectrometry (UHPLC-QTRAP/MS), and various nutritional compositions during storage at 0 °C under different vacuum conditions (0 kPa or −90 kPa) for 4 and 8 days were analyzed. Results showed that storage time had a significant effect on salmon metabolism. The total amino acids decreased by 62.95% and 65.89% at 0 kPa and −90 kPa, respectively. Notably, a marked reduction in histidine after 8 days at −90 kPa may have diminished bitterness, while decreased levels of umami-tasting amino acids like glutamine and aspartic acid affected the overall flavor profile. Overall, the packaging conditions at 0 °C and 0 kPa were more suitable for the preservation of most nutrients in salmon. Pathway enrichment analysis revealed that the reduction in substances was mainly related to the alanine, aspartate, and glutamate metabolism pathways. Alanine, inosine, and histidine, whose levels changed significantly, can bind to the typical umami taste receptor TIR1/TIR3 and can be biomarkers to monitor and determine the freshness or spoilage of salmon after 4–8 days of storage. This study revealed the changes in small-molecule nutrients in salmon during storage under different packaging conditions, which provides a reference for the packaging preservation technology of fresh salmon and new ideas for the evaluation of salmon quality and determination of freshness.

This study systematically deciphers a comprehensive analysis of biochemical and sensory variations in Takifugu obscurus, evaluating the seasonal dynamics, salinity gradients (0 and 3‰), and nutritional regimes on quality determinants in aquaculture. To the best of our knowledge, the mechanistic links between cultivation factors and organoleptic quality were first established through integrative biochemical profiling, including proximate composition, free amino acids, taste-active nucleotides, and mineral ions, coupled with quantitative sensory evaluation. The results revealed that spring samples exhibit 44.7% higher inosine monophosphate than that of autumn and 92.8% elevated ATP, correlating with superior umami-kokumi attributes. Salinity adaptation drove metabolic trade-offs: freshwater cultivation amplified flavor-enhancing amino acids, while brackish systems prioritized ionic precision. Short-term fasting induced alanine accumulation without sensory compromise, demonstrating nutritional plasticity. Polyculture compatibility was evidenced by negligible quality divergence from monoculture, despite enhanced productivity. These insights advance sustainable aquaculture through science-driven strategies that harmonize ecological resilience, economic viability, and culinary excellence in commercial Takifugu obscurus production.