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The thin-lipped grey mullet, Liza ramada, a commercially significant fish in Egypt, was studied for its expression patterns along the brain-pituitarygonad axis in female L. ramada during the spawning season of 2022 in both captive and wild habitats. The inspected genes included Kiss2, Gpr54, Gnrh1, and Drd2 genes in the brain and ovary, as well as Lhβ, Fshβ, and Slα genes in the pituitary and ovary. Relative expressions of all studied genes either in the brain, or pituitary, and ovary were higher in ripe females than in immature ones. Captive females had higher Drd2 gene expressions; nevertheless, mature wild females had higher expression values for the other investigated genes that were measured in the brain, or pituitary and ovary. The study found correlations between gene expression patterns in wild and captive females (P< 0.05), suggesting that confinement may affect reproductive physiology. The findings suggest focusing on hormones for artificial fertilization therapies in confined females. [ABSTRACT FROM AUTHOR]

The current research work provided insights into the expression patterns of key genes in the BPG axis of Mugil cephalus females, highlighting differences between wild and captive environments during the spawning season. The investigated genes include Kiss2, Gpr54, Gnrh1, and Drd2 in the brain and ovary, as well as Lhβ, Fshβ, and Slα in the pituitary and ovary. The finding indicated that the relative expression of all examined genes is elevated in mature females compared to immature ones across all examined tissues (brain, pituitary, and ovary). The observation that the expressions of the examined genes in wild females of M. cephalus are highly correlated, either directly or inversely, with their counterparts in captive females, indicated a connection between gene expression patterns and the different environments (wild vs. captive). The results between wild and captive females were in significant values (P≤ 0.05). Overall, the observed correlations and significant differences in gene expression proposed potential impacts of captivity on the reproductive physiology of these fish. [ABSTRACT FROM AUTHOR]

The present study aimed to investigate the feeding biology of E. encrasicolus in the Egyptian Mediterranean coast at Port Said, Egypt. A total of 750 specimens of the European anchovy Engraulis encrasicolus (Linnaeus, 1758) were randomly sampled on monthly basis from March 2020 to February 2021 from the fish landing site at Port Said Mediterranean coast. The fish diet composition was formed of crustaceans (49.3%), followed by polychaetes (27.1%), phytoplankton (12.7%) and fish parts (11.0%). Crustaceans and polychaetes were found all year around and in all fish length groups. Phytoplankton disappeared in December, January and February. Fish parts disappeared in March and April. Crustaceans, polychaetes and fish parts increased with the increase in fish size, while phytoplankton decreased with the increase in fish size. In the present study, the maximum feeding activity was recorded during winter (75.8%) and the minimum in summer (32.0%). [ABSTRACT FROM AUTHOR]

A 90-days experiment was conducted to determine the impact of partial replacement of dietary fish meal (FM) with different concentrations of ultra-fine powder of Ulva lactuca, Laurencia obtusa and Cystoseira myrica on growth performance, feed utilization and RNA/DNA ratio of the hybrid red tilapia "Florida strain". A total number of 600 fish of Oreochromis sp., with an average weight of 5.67 ± 0.89 g and an average length of 6.4 ± 0.41 cm, were randomly divided into 30 aquaria (20 fish/ aquarium in triplicates). Ten experimental diets were formulated as control (C) that contains FM as the major source of protein and other dietsin which the FM was partially substituted (on the protein basis). Substitution was achieved with 5% Ulva lactuca (U5), 10 % U. lactuca (U10), 15% U. lactuca (U15), 5% Laurencia obtusa (L5), 10% L. obtusa (L10), 15% L. obtusa (L15), 5% Cystoseira myrica (C5), 10% C. myrica (C10) and 15% C. myrica (C15). Results of survival rate (SR) in all treatments were not significantly different but the control treatment showed the best SR%, while the lowest SR% was shown in C15 treatment. In case of Ulva lactuca, all growth parameters were at its highest values in U5 and decreased with the increase of inclusion levels. The growth values,when FM was partially replaced with C. myrica, were at their maximum at C15%. In Laurencia groups, the growth improved gradually with the increase in concentration and reached the highest level in Laurencia 15%. Moreover, the percentage of RNA/DNA increased significantly in Laurencia treatment compared with other treatments. In general, the results revealed that marine macroalgae could be considered as an acceptable alternative which can replace dietary FM protein in diets of the hybrid red tilapia. In addition, results showed that, the most effective group to be used is Laurencia obtusa which induced better growth performance with replacement levels up to 15% compared to the control diet. [ABSTRACT FROM AUTHOR]