In this study, three molecular markers including random amplified polymorphic DNA (RAPD), inter simple sequence repeat (ISSR) and simple sequence repeat (SSR) were used to evaluate genetic variation of green tiger prawn Penaeus semisulcatus collected from two geographically isolated environments; located in the Manifa, Arabian Gulf, Saudi Arabia and Ataka, Suez Gulf, Egypt. Genetic parameters included the percentage of polymorphism (P%), effective alleles (Ne), Nei genetic diversity (H) and Shannon index (I), which were calculated based on molecular data. All three marker systems distinguished genetic variation of P. semisulcatus in various levels. The highest polymorphism (91.30%) was obtained with SSR, followed by ISSR (82.26%) and RAPD markers (62.04%), respectively. Our results indicate that SSR appeared to be the best suited molecular assay for assessing the genetic variation between genotypes of P. semisulcatus. The present study indicated that Manifa and Ataka genotypes were closely related. Moreover, the analysis of variability could require more than one DNA‐based molecular marker techniques.

Understanding of fish genetic characterization plays a vital role in the conservation and utilization of fish genetic resources of grouper species. The present study was carried out to assess the genetic diversity and phylogenetic relationships in five grouper species, Epinephelus spp. from eastern Saudi Arabian coast using two molecular marker systems, inter simple sequence repeat (ISSR) and microsatellite (SSR) markers. In total, 219 individuals grouper specimens ( Epinephelus tauvina, E. coioides, E. bleekeri, E. malabaricus, and E. areolatus ) were genotyped with 10 ISSR and 11 SSR selected primers. The ISSR produced 94 DNA fragments, of which 44 were polymorphic with an average of 2.13 fragment per primer. While SSR primers generated 107 alleles, all of them were polymorphic with an average 9.72 per primer. ISSR and SSR techniques demonstrated a high level of gene diversity and genetic distances illustrated by UPGMA dendrograms among the grouper species. The results proved that the SSR markers were highly informative and efficient in detecting genetic variability and relationships of the Epinephelus spp.

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Water spinach, Ipomoea aquatica, is a common semi‐aquatic weed that is used as an ingredient in fish feed to support its growth and defence system. The present study aimed to identify and quantify bioactive polyphenols through HPLC‐DAD (High Performance Liquid Chromatograpgy ‐ Diode Array Detector) analysis and to evaluate the antioxidant activity of the aquatic weed I. aquatica available in Bangladesh. Different bioactive phytochemical groups were qualitatively appraised in crude ethanol extract, aqueous and n‐hexane fractions of water spinach. The total polyphenol and flavonoids content were spectrophotometrically discerned using Folin–Chiocalteu and aluminium chloride, respectively. Bioactive compounds of the extracts were identified by the HPLC‐DAD method. Furthermore, 2,2‐diphenyl‐1‐picryldydrazyl (DPPH) and hydroxyl‐radical scavenging and reducing power assays were followed to assess antioxidant activity. The experimental extracts confirmed the presence of different bioactive phytochemical groups. The crude extract contained the highest content of both polyphenol (94.93 mg gallic acid (GA) equivalent per gram dry extract) and flavonoids (373.30 mg quercetin equivalent per gram dry extract). Besides, in HPLC (High Performance Liquid Chromatogrphy) analysis, ellagic acid was present at the highest concentration both in crude (337.26 mg/100 g dry extract) and aqueous (280.06 mg/100 g dry extract) extracts. However, the n‐hexane fraction only contained GA (13.91 mg/100 g dry extract). Also, some other bioactive polyphenols were identified in crude and aqueous fraction extracts. The crude extract revealed superior antioxidant activity in DPPH (Half maximal inhibitory Concentration (IC50) = 149.30 ± 1.43 μg/ml) and hydroxyl radical scavenging assays (IC50 = 327.257 ± 1.36 μg/ml) in comparison to the rest of the extracts. Furthermore, all of the extracts showed dose‐dependent reducing power activity. HPLC‐identified bioactive compounds may be responsible for antioxidant activity. Because of these identified compounds, I. aquatica holds the potential feed ingredient in aquaculture.

The present study examines the population dynamics of the green tiger prawn, Penaeus semisulcatus, in western Arabian Gulf. Monthly length-frequency samples were collected from Dareen port, between May 2013 and April 2014. Maximum carapace lengths recorded were 38 and 36.67 mm for males and females respectively. The growth analysis using von Bertalanffy model showed different growth patterns between males (CL¥= 51.50 mm; k = 1.77 yr-1) and females (CL¥ = 62 mm; k = 1.10 yr-1). Total mortality was also found to differ between the two genders with 4.65 yr-1 for males and 3.37 yr-1 for females. Estimates of natural mortality of males and females were 2.12 yr-1 and 1.47 yr-1 respectively. In all, the results found herein were consistent with the few published studies on the life history of Penaeus semisulcatus in the Arabian Gulf