The quality monitoring of frozen marine products has become essential in the fishery industry, where efficient and effective quality assurance is becoming increasingly important. In this study, we proposed a novel method of evaluating fish quality by combining the fluorescence excitation-emission matrix (EEM) with imaging techniques to visualize the spatial-temporal changes of freshness indices such as K-value and taste component IMP content. The result showed that the distribution of K-value and IMP content could be visualized with accuracy of R² = 0.78 and R² = 0.83, respectively. Furthermore, this innovative approach was applied to differentiate burnt meat, which is a type of abnormal meat found in many types of fish, and it was found that burnt meat could be detected even when in a frozen condition.

The present study was conducted to characterize fluorophores in the fish body using three-dimensional fluorescence fingerprints (3D-FFs) and to utilize these 3D-FFs obtained from frozen horse mackerel (Trachurus japonicus) fillets to predict early post-mortem changes. Alive fish were sacrificed instantly, preserved in ice until 2 days, and then filleted, vacuum packed, and frozen. Subsequently, 3D-FFs of the frozen fillets were acquired using F-7000 aided with a fiber probe. Post-mortem freshness changes were tracked by measuring adenylate energy charge (AEC) values and nicotinamide adenine dinucleotide (NAD and NADH) content. Partial least squares regression models for predicting AEC values and NADH content in frozen fish meat showed good fittings, with R² of 0.90 and 0.85, by utilizing eight and five excitation wavelengths, respectively, based on their fluorescence features acquired from standard fluorophores. This novel approach of 3D-FFs could be utilized as an efficient technique for at-line monitoring of frozen fish quality.

Effects of water treatment by two probiotic products (PondPlus® and AquaPhoto®) and sand filtration were studied on growth performance of tilapia (Oreochromis niloticus) and pangas (Pangasianodon hypophthalmus) stocked at tilapia:pangas ratio of 5:3 in traditional earthen ponds in Bangladesh. The fish were stocked at a density of 20,000 fish ha⁻¹ and reared for 7 months. Compared to untreated ponds, treatments of probiotic products or sand filtration in earthen ponds resulted in a higher O₂ content, higher water transparency, less ammonium, and fewer cyanobacteria. Weight gain for individual tilapia was lowest in the AquaPhoto-treated ponds (177 g), while similar gains (188–194 g) occurred in the other ponds. For pangas, the lowest weight gain (627 g) was obtained in the sand filter-treated ponds, as compared to 690–797 g in the other ponds. Thus, a general positive effect from the treatments on fish growth was not observed, possibly due to a reduced content of detritus (supplementary feed for both fish species) in the treated ponds.