Effective concentration of herbal anaesthetics Origanum vulgare L. oil and its effects on stress parameters in Nile tilapia (Oreochromis niloticus).

BACKGROUND: Using anaesthetics is an important application in aquaculture especially where the fish transportation, vaccination, grading, sorting activities and many other handling operations have been conducted during the different stages of production periods in the farms or hatcheries. OBJECTIVES: This study aimed to evaluate the efficacy of oregano essential oil (OO) as an anaesthetic for Nile tilapia and to determine the optimal concentration and post-application stress effects compared to clove oil (CO). METHODS: Nile tilapia juveniles were exposed to different concentrations of OO (20-40-60-80-100 mg L-1) and CO (50 mg L-1) for different time periods to determine the optimal concentration and exposure time. After the effective concentration of OO was determined, in the second experiment, stress parameters (glucose, plasma cortisol) were analysed after 0, 2, 6, 12 and 24 h of application. The results compared to the control group and CO results. RESULTS: The study found that OO which has carvacrol compound higher than 78% was an efficient anaesthetic for Nile tilapia, and the effective concentration was found to be 60 mg L-1. No significant differences were found between opercular beats in any concentration of OO and CO. Basal glucose level in blood without anaesthesia application and recorded at 39.33 mg dL-1 and significantly lower than OO and CO at first two sampling points, 0 and 2 h (p < 0.05). According to plasma cortisol level results, although CO experimental group showed secondary stress response at 12 h (17.91 ± 4.21 ng mL-1), OO and CO group cortisol levels decreased at 24 h after anaesthesia application 7.13 ± 0.14and 7.01 ± 0.54 ng mL-1, respectively, below the control group cortisol concentration (12.28 ± 1.81 ng mL-1). CONCLUSIONS: These findings have important implications for the aquaculture industry as the use of OO as an anaesthetic could reduce the stress and mortality associated with traditional anaesthetics. Further research is needed to evaluate the efficacy of OO as an anaesthetic agent for other fish species and to determine the optimal concentration and exposure time for different species.

The impact of the different types of acid solution on the extraction and adsorption performance of chitin from shrimp shell waste.

The properties of chitin-based adsorbents varied among studies since they are influenced by different factors, such as the types of base and acid used to extract the chitin. Therefore, this works aimed to investigate the impact of four different acid solutions on the extraction and properties of chitin from shrimp shell waste, and to evaluate the adsorption performance of the obtained chitin on removing dye from an aqueous solution. The result showed that H2SO4, HCl, and HNO3 could remove high minerals from the shrimp shell, while the effect of CH3COOH was inferior. The Fourier Transform Infrared (FTIR) and X-ray diffraction (XRD) indicated that the extracted chitin was α-amorphous structure, regardless of the type of acid solution. However, the type of acid solution influenced the crystallinity index of the extracted chitin. The Scanning Electron Microscope (SEM) showed both fibrillar material and porous structures. In addition, the chitin extracted through demineralization using H2SO4 was more effective in removing RBBR dye from aqueous solution, followed by HCl, HNO3, and the last, CH3COOH treatment. The performances of chitin-based adsorbent could be attributed to the strength of acid solution used to remove mineral during the extraction process and the obtained pore structures.

Induction of spermiation using Ovaprim™ with topical gill method in the silver rasbora (Rasbora argyrotaenia).

The main obstacles on silver rasbora (Rasbora argyrotaenia) culture are having the limited number of broodstock and spawning depending on the season. The purpose of this study was to determine the effect of different dosage of Ovaprim™ induction by topical gill method to silver rasbora spermiation in order to continue the production out of its reproduction season with an optimum dose. A total of 30 male fish with a weight of 7.78 ±â€¯0.20 g and length 4.11 ±â€¯0.31 cm was used in this research. Topical gill treatments of Ovaprim™ were administered with following doses; 0.15 µl/g, 0.25 µl/g, 0.35 µl/g, 0.45 µl/g and 0.55 µl/g body weight. Milt volume, sperm concentration, sperm motility, and sperm viability parameters were observed in this study to understand the optimum dose of Ovaprim™ for male silver rasbora breeders. Spermiation induction of silver rasbora using Ovaprim™ with topical gill method has been successfully carried out, indicating an increase (P < 0.05) in milt volume, sperm concentration, sperm motility, and sperm viability. According to results a dose of Ovaprim™ is recommended to be used the 0.25 µl/g body weight in the spermiation induction of silver rasbora.