This study investigated the effect of substances on nonspecific immune responses of head kidney leukocytes, the antimicrobial activity against Vibrio sp., as well as the time-kill of Vibrio sp. by combining the substances with lactic acid bacteria (LAB) and Pediococcus sp. The substances are B. pilosa hot water extract, B. pilosa powder extract, B. pilosa methanol extract, B. pilosa ethanol extract, B. alba hot water extract, B. alba powder extract, B. alba methanol extract, B. alba ethanol extract, and bioactive compounds, namely cytopiloyne, flavonoid, phenol, ethyl caffeate, luteolin, chlorogenic acid, butein, and linoleic acid. The results showed that some of them were nontoxic to the head kidney leukocytes, which can increase the phagocytic rate, phagocytic index, and respiratory burst. These substances were able to inhibit the growth of Vibrio sp.; they can even completely kill the pathogenic bacteria. The largest of the inhibition zone formed from the EC group at a concentration range of 5–50 µg/mL against V. parahaemolyticus, V. alginolyticus, and V. harveyi with a value of 19.7 ± 0.56, 19.3 ± 1.53, and 20.6 ± 1.53 mm. Furthermore, the time-kill studies showed that the LAB and P. acidilactici can completely kill the Vibrio sp. at 6 h incubation time, mainly in the group of combination with EC.

Fish identification in the Red Sea, particularly in Saudi Arabia, has a long history. Because of the vast fish diversity in Saudi Arabia, proper species identification is required. Indeed, identifying fish species is critical for biodiversity conservation, food and drug safety, and sustainable fishery management. Numerous approaches have been used to identify fish species, including conventional morphological identification, next-generation sequencing (NGS), nanopore sequencing, DNA barcoding, and environmental DNA analysis. In this review, we collected as much scientific information as possible on species identification in Saudi Arabia. Our findings suggest that the identification process has advanced and spread rapidly and broadly, as evidenced by the discovery of new fish species in Saudi Arabia. The advantages and disadvantages of each method were discussed as part of a comprehensive comparison. This study aimed to provide further scientific knowledge to promote the growth of fish diversity worldwide. Keywords: fish diversity, identification process, Saudi Arabia.

Mercury (Hg) is a dangerous heavy metal that can accumulate in fish and is harmful when consumed by humans. This study investigated the bioaccumulation of mercury in the form of methylmercury (MeHg) and evaluated nonspecific immune responses such as phagocytic activity and superoxide anion (O₂⁻) production in hybrid grouper (Epinephelus fuscoguttatus × E. lanceolatus). The hybrid grouper leukocytes were incubated with methylmercury chloride (CH₃HgCl) at concentrations of 10–10,000 µg/L to determine cell viability, phagocytic activity, and O₂⁻ production in vitro. Subsequently, the grouper were exposed daily to CH₃HgCl mixed in the experimental diets at concentrations of 0, 1, 5, and 10 mg/kg for 28 days. The bioaccumulation of MeHg in the liver, head kidney, and muscle tissue was measured, and the phagocytic activity and O₂⁻ production were evaluated. In vitro results indicated that cell viability was significantly lower than that of the control group at concentrations > 500 µg/L. The phagocytic rate and O₂⁻ production at concentrations ˃ 500 and ˃ 200 µg/L, respectively, were significantly lower than those of the control group. The dietary exposure demonstrated that MeHg accumulated more substantially in the liver and head kidney compared with the muscle tissue in the treatment groups. Moreover, the cumulative concentration significantly increased with higher concentrations and more days of exposure. The phagocytic rate and O₂⁻ production in the treatment groups were significantly lower than those in the control group from days 2 and 1, respectively. In conclusion, hybrid grouper accumulated significant MeHg in the liver and head kidney compared with the muscle tissue, and higher concentrations and more exposure days resulted in decreased cell viability, phagocytic activity, and O₂⁻ production.