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The current study aimed to assess the influence of dietary inclusion of cyanobacterium Arthrospira platensis NIOF17/003 as a dry material and as a free-lipid biomass (FL) on the growth performance, body composition, redox status, immune responses, and gene expression of whiteleg shrimp, Litopenaeus vannamei postlarvae. L. vannamei were fed five different supplemented diets; the first group was fed on an un-supplemented diet as a negative control group (C-N), the second group was fed on a commercial diet supplemented with 2% of A. platensis complete biomass as a positive control group (C-P20), whereas, the three remaining groups were fed on a commercial diet supplemented with graded amounts of FL at 1%, 2%, and 3% (FL10, FL20, and FL30, respectively). The obtained results indicated that the diet containing 1% FL significantly increased the growth performance, efficiency of consumed feed, and survival percentage of L. vannamei compared to both C-N and C-P20 groups. As for the carcass analysis, diets containing A. platensis or its FL at higher levels significantly increased the protein, lipid, and ash content compared to the C-N group. Moreover, the shrimp group fed on C-P20 and FL10 gave significantly stimulated higher digestive enzyme activities compared with C-N. The shrimp fed C-P20 or FL exhibited higher innate immune responses and promoted their redox status profile. Also, the shrimp fed a low FL levels significantly upregulated the expression of both the peroxiredoxin (Prx) and prophenoloxidase (PPO1) genes than those receiving C-N. The current results recommended that dietary supplementation with 1% FL is the most effective treatment in promoting the performance and immunity of whiteleg shrimp. [ABSTRACT FROM AUTHOR]

Several studies investigated the usage of spirulina (Arthrospira platensis) in aquaculture as a functional dietary additive or plant proteins replacers; however, more efforts still needed to test its nano form inclusion in aquafeed. In this study, Nile tilapia (Oreochromis niloticus) fed dietary spirulina (A. platensis) nanoparticles (SNP) at 0 (control), 0.1, 1 and 10 g/kg diet while the fifth diet was mixed with 10 g/kg of the normal form of A. platensis as a positive control. The final weight (FW), weight gain (WG) and feed conversion ratio of fish fed SNP at 10 g/kg displayed improved values comparing with the other groups (p < 0.05). Further, fish fed 1 g SNP had higher FW and WG than the control and 0.1 g SNP and 10 g normal A. platensis. The incorporation of SNP at 1 and 10 g/kg in Nile tilapia diets significantly (p < 0.05) enhanced total protein, albumin, globulin, lowered the values of serum glucose and activities of ALT and AST compared with control and spirulina groups. The SOD, CAT, GPx, lysozyme and respiratory burst activities were meaningfully promoted (p < 0.05) in fish received 1 and 10 g/kg diet concerning the control and spirulina groups. Nile tilapia challenged with Aeromonas hydrophila showed congestion of the kidney, liver and spleen tissues while SNP alleviated the inflammation induced by A. hydrophila. Different levels of SNP‐incorporated group showed lower cumulative mortality than the other groups. In conclusion, the obtained results illustrated that spirulina in nano form is recommended to enhance Nile tilapia well‐being. [ABSTRACT FROM AUTHOR]

This study was conducted at Attaka harbor in the Gulf of Suez (Red Sea) during the 2018-2020 fishing seasons to assess the technical specifications of trawl nets, morphometric characteristics of haffara sea bream (Rhabdosargus haffara), and their selectivity parameters. Results indicated that these trawl nets have different design characteristics; it depends on the technical characters of the trawler (i.e. horsepower, length of trawler). The hanging ratio of the bottom trawl ranged from 0.44 to 0.76 while the horizontal opening of the net ranged from 17.91 to 30.94 m. The length-weight relationship (LWR) of Rhabdosargus haffara had a significant correlation and the exponent b was observed to be 3.03. On the other hand, length-girth and length depth were analyzed and the correlation coefficients were determined to be 0.85 and 0.80, respectively. Lengths at first capture (L50) for male, female, and combined sexes were 12.67, 14.45 and 13.17 cm, respectively; which were higher than the minimum landing size. This information may be used by fishery managers to get an approximate estimate of the bottom trawl effect and to design appropriate marine spatial planning. [ABSTRACT FROM AUTHOR]