Novel study was performed to evaluate the efficacy of ginger (GN) and its nanoparticles (GNNP) on growth, cognition, immunity and prevention of motile Aeromonas septicaemia (MAS) in Cyprinus carpio fingerlings. Fish were divided into five groups fed diet 1 (control; no additives), diet 2 (0.5 g of GN), 3 (1 g of GN), 4 (0.5 g of GNNP) and 5 (1 g of GNNP) per kg feed for 30 days. In the behavioural test, fish were individually placed in a foraging maze to evaluate their cognition capability and feeding behaviour. At the end of feeding period, fish fed GN and GNNP showed significant better final weight than the controls. GN and GNNP significantly increased total protein, globulin and lysozyme, whereas 1 g GNNP group was the highest. One gram of GN, 0.5 g and 1 g GNNP enhanced cognition capability, while GN and GNNP increased percentage of fish fed in the maze. Brain acetylcholinesterase was significantly decreased than control in 1 g GN group. GNNP succeeded in the prevention of MAS more than GN, because no mortalities and 100% relative percentage survival (RPS) were detected in 1 and 0.5 g GNNP and 1 g GN per kg feed, while fish fed 0.5 g GN showed 20% mortalities and 71.4 RPS.

The current study aimed to investigate the efficacy of dietary thyme essential oil (TEO), Nigella sativa essential oil (NSEO), thyme essential oil nano-emulsion (TEO-NE), and Nigella sativa essential oil nano-emulsion (NSEO-NE) in reducing total ammonia nitrogen (TAN), improving immune response, mitigating stress, and acting as anti-inflammatory agents as well as preventing streptococcosis infection in Oreochromis niloticus (O. niloticus). Fish (N = 330, 14 ± 2 g) were divided into 10 groups of 11 fish each, with three replicates in each group. The negative and positive controls were fed a control diet, while the third group was given 1% TEO. Moreover, the fourth group of fish was given 2% TEO. The fifth and sixth groups were fed 1% TEO-NE and 2% TEO-NE, respectively. The seventh, eighth, ninth, and tenth groups were fed 1% NSEO, 2% NSEO, 1% NSEO-NE, and 2% NSEO-NE, respectively. After dietary intake of TEO, NSEO, and their nano-emulsions for 28 days, the mean values of TAN levels in the water of fish aquaria had a significant reduction in the group fed 2% TEO-NE compared to the control group. On the contrary, NSEO-NE at the same concentration had no significant effect on TAN levels. The levels of lysozyme, complement 5, and IgM increased in all feeding groups compared to the control group. Concerning cortisol level as a stress indicator, it was decreased in all feeding groups compared to the control. Also, the current experiment overall showed a significant decrease in the expression level of pro-inflammatory tumor necrosis factor (TNF-α) gene in the gills of fish groups fed TEO, TEO-NE, NS, and NS-NE relative to the β-actin gene. Oppositely, there was an increase in the expression level of the anti-inflammatory transforming growth factor (TGF-β). In the current study, TEO-NE and NSEO-NE showed a better effect on preventing streptococcosis in O. niloticus with no mortality than 1% TEO and NSEO, respectively. Furthermore, there was a 12.5% mortality rate and an 84.99 RPS in the group fed 1% TEO and injected with Streptococcus inae. On the other hand, the groups fed 1 and 2% NSEO showed 37.5 and 25% mortality rate, respectively and 54.99 and 69.99 RPS. In conclusion, the nano-emulsion either TEO or NSEO had the superior effect. For bulk status, the TEO had superior effect than NSEO. The study needs more investigations for ammonia, either on the mode of action or over a longer period.

This study was carried out to evaluate the safety and effectiveness of trichlorfon in prevention of lernaeosis among hatchery-reared cyprinids. Also, it compared with plant extracts (carvacrol and cymene mixture and thyme) in lernaeosis control. At the Abo-Saleh fish hatchery in BeniSuef, Egypt, the trichlorfon bioconcentrations of cyprinids fries and fingerlings, as well as soil, water and plant samples were examined for 2 years. Trichlorfon was detected in fingerlings, water and plant samples, except soil sampled 1 hr after trichlorfon was applied to the fish pond. The highest concentration of trichlorfon was in fish, followed by water and plant samples. No trichlorfon was detected in fingerlings, water, plant and soil sampled after 5 days and 5 months. Fingerlings and brooders of cyprinids were examined in situ for clinical abnormalities and prevalence of lernaeosis. In addition, the intensity of the lernaea infestation was determined. Macroscopic Lernaea cyprinacea females were seen attached to the skin and fins associated with swollen hyperemic nodules and open wounds. Lernaeosis appeared sporadically during examination seasons with a high intensity. Under experimental condition, trichlorfon succeeded in controlling lernaeosis among Ctenophyrngedon idella fingerlings, as it eliminated 100% of Lernaea cyprinacea in comparison with 74.28% and 50.2% in carvacrol and cymene mixture and thyme treated fish respectively.