Purpose Aquaponics combine aquaculture with crop production in a mutual system. In this experiment, the growth of Amaranthus in aquaponics with tilapia fish was investigated. Methods 500-liter water tanks containing tilapia fish at four initial stocking densities of 100, 150, 200, and 250 fish/m 3 were used in triplicates, with a view to evaluate vegetable yields as influenced by fish biomass to water ratio. 1 g of Amaranthus seeds were sown in a 1 m 2 planting trough, which contained gravel with a top layer of sandy soil. The pots were flooded with water from fish holdings by an aquarium pump. Results The germination rate of Amaranthus was not significantly different across the experimental setup (P > 0.05). The growth rate of Amaranthus was significantly higher with increasing fish density (P < 0.05). The average lowest and highest of shoots dry biomass yield recorded were 0.36 and 1.95 g/plant at 8 weeks after of sowing, and this corresponds to fish stocking densities of 100 and 250 fish/m 3 , respectively. A high positive correlation was found between the shoot dry biomass of Amaranthus and fish stocking density. The survival of tilapia fingerlings was not significant different, while the production levels were 5.62, 4.77, 4.57, and 4.00 kg/m 2 in 100, 150, 200, and 250 fish/m 3. Conclusions The growth of Amaranthus in this experiment demonstrated that the plant could effectively utilize the nitrogenous waste from fish tanks for biomass production, even at a higher concentration, while considerations for moderate fish density are only for fish health.
Summary The reproductive biology of cobia, Rachycentron canadum, from the coastal waters of Dungun, Malaysia was studied from June 2014 to May 2015. From commercial trawls, a total of 201 samples (combined sexes) were collected (fork lengths [FL] 37.5–124.0 cm; body weights 0.5–20.4 g). The overall sex ratio of females to males was 1:0.9, which was not significantly different (χ2 = 2.12, df = 1; p < .05). Estimations of length at 50% maturity (L50) showed that both sexes matured at approximately 75 cm FL; estimated spawning frequency was 6 days. Mean batch fecundity (BF) ranged from 0.55 to 4.32 million eggs. The average number of eggs per gram of ovary was from 2,100 to 5,400 eggs, and relative fecundity 147 eggs/g. There was a weak positive correlation (r2 = .48) between BF and female FL as well as BF with an ovary‐free body weight (r2 = .56), possibly due to females being in a continuous spawning condition and some possibly half‐spent, based on the histological examination of the female gonads. Despite cobia being asynchronous spawners, the gonadosomatic index in both males and females showed peaks in June, November, and particularly March. Based on histological examination, spawning‐capable males were encountered throughout the study period, whereas spawning‐capable females in the late developing subphase were found mostly in March and April. This is the first study on the reproductive aspects of cobia in Malaysian waters.
Cobia, Rachycentron canadum, is an important recreational marine fish of growing popularity in the aquaculture industry. Knowledge of the impact of environment on their fatty acids (FAs) utilization may contribute to the understanding their feeding in culture condition especially as cobia is been considered for low salinity culture. This study investigates the variations in the fatty acid contents of cobia from Dungun coast, Malaysia with respect to the changes in seasons and feeding intensity. Saturated fatty acids (FAs) comprised the majority of FAs in muscle, followed by monoenes, total poly-unsaturated fatty acids (PUFAs) (n-3) and then total PUFAs (n-6) with no seasonal variation in the quantity. A similar trend was observed in liver but total saturated FAs was significantly higher during the inter-monsoon while total monoenes significantly accumulate during monsoon. During low feeding intensity, there was a significant accumulation of PUFAs (n-6) in the muscle tissue (P < 0.05). Gut content analyses showed that cobia significantly increased the consumption of mollusks during the inter-monsoon (P < 0.05), although bony fishes dominated their diet throughout the year with no significant seasonal differences (P > 0.05). Our results suggest that cobia lipids are composed of a significant quantity of omega-3 and omega-6 FAs, which are considered to have important health benefits. While the environmental variability especially salinity fluctuations and prey abundance that accompany seasonal changes have a significant impact on the nutritional composition of cobia in Malaysian waters, their nutritional quality is maintained.PeerJ Preprints | https://doi.org/10.7287/peerj.preprints.2726v1 | CC BY 4.0 Open Access |
Cobia, Rachycentron canadum, is an important recreational marine fish of growing popularity in the aquaculture industry. Knowledge of the impact of environment on their fatty acids (FAs) utilization may contribute to the understanding their feeding in culture condition especially as cobia is been considered for low salinity culture. This study investigates the variations in the fatty acid contents of cobia from Dungun coast, Malaysia with respect to the changes in seasons and feeding intensity. Saturated fatty acids (FAs) comprised the majority of FAs in muscle, followed by monoenes, total poly-unsaturated fatty acids (PUFAs) (n-3) and then total PUFAs (n-6) with no seasonal variation in the quantity. A similar trend was observed in liver but total saturated FAs was significantly higher during the inter-monsoon while total monoenes significantly accumulate during monsoon. During low feeding intensity, there was a significant accumulation of PUFAs (n-6) in the muscle tissue (P < 0.05). Gut content analyses showed that cobia significantly increased the consumption of mollusks during the inter-monsoon (P < 0.05), although bony fishes dominated their diet throughout the year with no significant seasonal differences (P > 0.05). Our results suggest that cobia lipids are composed of a significant quantity of omega-3 and omega-6 FAs, which are considered to have important health benefits. While the environmental variability especially salinity fluctuations and prey abundance that accompany seasonal changes have a significant impact on the nutritional composition of cobia in Malaysian waters, their nutritional quality is maintained.PeerJ Preprints | https://doi.org/10.7287/peerj.preprints.2726v1 | CC BY 4.0 Open Access |
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.