Aquaculture Research最新文献

The aquaculture industry will be crucial in helping the world’s food supply and keep up with the demand. Aquaculture, like agriculture, must expand and develop sustainably in all the countries to keep up with the rising demand for food. To this end, the aquaculture industry has forged new scientific and technological frontiers in pursuit of long-term food security. Among these is organic aquaculture, whose distinctive protocol has great potential to advance aquaculture. Organic aquaculture is being explored for multiple reasons, encompassing the aim to minimize environmental footprints, fulfill escalating consumer appetites for seafood, and contend within the industry this paper endeavors to address the gaps in current literature by offering an exhaustive overview of various aspects of organic aquaculture. This encompasses its regulation, production methods, food quality, environmental impact, economic viability, as well as socioeconomic and marketing aspects. It is necessary to acquire more knowledge about organic farming techniques before switching over to organic aquaculture on a large scale. Organic regulation, production, food quality, economic performance, and social and marketing issues are at the top. This review found that consumers lack understanding of organic principles, and regulations are inconsistently applied. However, organic aquaculture promotes social equality by protecting producers’ rights to work without discrimination based on gender, race, or sexual orientation factors that ultimately boost the industry’s popularity. Organic aquaculture viability varies depending on factors like feed costs, fixed expenses, and the premium pricing sensitivity, making it unfeasible for certain species. However, from both societal and economic standpoints, organic aquaculture appears most suitable for implementation in developing nations.

The effects of nanoscale synthetic zeolite powder (NZeP) levels in diet on water quality, growth performance, muscle proximate composition, and some blood biochemical indices of Nile tilapia (Oreochromis niloticus) fingerlings were evaluated in a 60-day experiment. One hundred eighty fish with an average weight of 5.91 ± 0.45 g were distributed in three different groups of control (basal diet without NZeP), NZP_0.5% (basal diet + 0.5% NZeP), and NZeP_1% (basal diet + 1% NZeP) with triplicate. The zeolite particles were characterized via field emission scanning electron microscopy coupled with X-ray energy dispersive spectroscopy (FE-SEM/EDS), dynamic light scattering (DLS), and X-ray diffraction (XRD) techniques. The results revealed that the total ammonia nitrogen (TAN) concentration in the NZeP dietary groups decreased compared to the control group after the 20th day of the experiment (p  < 0.05). The TAN concentration in the NZeP_1% group was lower than in the NZeP_0.5% group on days 50 and 60 (p  < 0.05). The final weight, weight gain, and average daily gain parameters were lower in the fish fed on NZeP_1%-supplemented diet than in other dietary groups (p  < 0.05). The feed conversion ratio value decreased in the NZeP dietary groups compared to the control (p  < 0.05). The lowest FCR value was recorded in the NZeP_1% dietary group (p  < 0.05). The muscle crude protein content increased in the fish fed on diet supplemented with NZeP_1% in comparison to the control (p  < 0.05). The aspartate aminotransferase (AST) concentration decreased in the plasma of fish fed on NZeP-supplemented diets compared to the control (p  < 0.05). The plasma glucose concentration was lower in the NZeP_1% dietary group than the control (p  < 0.05). In conclusion, the adding nanozeolite powder at a level of 1% to diet had positive effects on water quality, the growth performance, and muscle proximate composition of Nile tilapia fingerlings.

This study evaluated the impact of increasing dietary β-mannanase (BM) supplementation (Natupulse TS, BASF, Ludwigshafen am Rhein, Germany) on fecal viscosity and pH, apparent digestibility coefficients (ADCs) of energy and nutrients, including amino acids, fecal nutrient loss in contents of soybean meal (SBM)-based diets fed to juvenile Nile tilapia, Oreochromis niloticus. A total of 504 fingerlings (initial body weight of 31.5 ± 4.2 g) were randomly distributed into 24 aquaria (70 L each) in a completely randomized design using six dietary treatments and four replicates of 21 fish per aquarium. Fish were fed diets containing BM at 0, 1600, 3200, 4800, 6400, and 8000 TMU (thermostable endo-1,4-BM units) kg⁻¹ and hand-fed six times a day until apparent satiety for 30 days. Chromium oxide was employed as an indigestible marker. The ADC of gross energy, crude protein, crude lipids, and essential amino acids exhibited a quadratic effect with the maximum point in fish fed 4818, 4722, 4615, and 4816 TMU kg⁻¹ BM, respectively. The digestible energy (DE) content of diets presented a quadratic effect, and the maximum point was obtained in fish fed 4803 TMU BM kg⁻¹ diet, which improved the DE content by +1.2 MJ kg⁻¹ relative to the BM-unsupplemented diet. The fecal pH, fecal viscosity, organic matter loss, and nitrogen loss presented a quadratic effect with the minimum point in fish fed 4810, 4839, 4750, and 4801 TMU BM kg⁻¹ diet, respectively. Principal component analysis indicated that dietary BM at 4800 and 6400 TMU BM kg⁻¹ diet was associated with improvements in the ADC of gross energy, crude protein, and crude lipids. In conclusion, including 4803 TMU BM kg⁻¹ diet effectively improves DE content and optimizes nutrient digestibility and feces pH and viscosity in Nile tilapia fed an SBM-based diet.

Tilapia and lettuce are the most frequently used combination among aquaponics producers, hobbyists, and educators. Therefore, this literature review aims to aggregate the knowledge on the current status of tilapia/lettuce production and identify research gaps. Among the 40 reviewed publications, 72.5% used Nile tilapia, 17.5% used red, 2.5% used red Mozambique, 5% used rocky mountain strain, and 5% of the articles stated that they used tilapia without reporting the species. Tilapia initial density used ranged from 0.34 to 28.4 kg/m³, which depended on the purpose of the study, experimental size, and design. For the hydroponic unit, 55% of the publications utilized deep water culture (DWC), 35% utilized nutrient film technique (NFT), and 10% utilized media bed (MB). The optimum ratio between fish feeding rate and plant growing area (60 g of feed/day/m²) was originally calculated at the University of Virgin Island and published in 1988 using Bibb lettuce. This recommended ratio has been used by farmers and researchers as a rule of thumb for years. However, this recommended ratio did not take into account other factors such as fish species, protein content of the diet, plant species/variety, plant density, biological filtration, and airflow in the grow bed. Hence, the current review suggests that the fish-to-plant ratio, fish density, and flow rate in the aquaponic systems needs to be reevaluated. As there is a thermal preference mismatch between tilapia and lettuce, there is a need to evaluate the optimum temperature for both to obtain the highest growth performance. Nowadays, it is believed that the farmed stocks’ genetic quality needs to be regularly enhanced and protected. Consequently, feeding frequency, feeding amount, and stocking densities in aquaponic systems should be continuously reevaluated with the improved strains of tilapia as well as heat-tolerant varieties of lettuce.

Starvation is common in fish, particularly during the juvenile period, and is typically caused by environmental changes. However, the molecular mechanisms of juvenile Micropterus salmoides in response to starvation are still poorly understood. We elucidated changes in the serum physiology, transcriptome, and intestinal microbiome of M. salmoides after 14 days of starvation. Body weight and serum concentrations of glucose, cholesterol, triglycerides, and alkaline phosphatase significantly decreased during the starvation period. However, serum concentrations of aspartate transaminase and alanine transaminase were significantly elevated. Transcriptome analysis of liver tissues from commonly fed fish and starved fish revealed 1069 differentially expressed genes (DEGs), of which 211 were up-regulated. In total, 586 DEGs were identified in the intestinal tissues, of which 166 were up-regulated and 420 were down-regulated. KEGG analysis revealed that starvation affected multiple pathways, particularly those related to energy, metabolism and immunity. Starvation limited fatty acid biosynthesis and elongation in the liver, down-regulated immunity-related genes in the intestine and promoted fatty acid degradation. The 16S rDNA analysis revealed that starvation altered intestinal microbiota homeostasis and increased intestinal Shannon diversity. Two opposite patterns of dominant genera emerged in commonly fed fish (most abundant genus is Mycoplasma) and in starved fish (most abundant genus is Cetobacterium). Starvation also increased the abundance of pathogens, including Plesiomonas and Aeromonas. Our study will provide the theoretical basis for assessing the starvation levels and nutritional status of juvenile fish and guidance for further studies on starvation in the context of fish physiology and health.

The present study explored the potential of wild Mysis diluviana, a widespread freshwater crustacean that is also invasive in many lakes, to serve as a substitute for fishmeal in the formulation of salmonid aquafeed. M. diluviana, harvested from Okanagan Lake in British Columbia, Canada, had a high protein content, with crude protein making up 53% of its dry body weight; lipids formed 32% of dry M. diluviana body weight. Fingerlings from two distinct strains of rainbow trout were fed for 60 days with one of three diet treatments: experimental feeds in which 25% or 50% of the fishmeal ingredient was replaced with M. diluviana and a feed containing no M. diluviana. Feeds containing M. diluviana supported the same survivorship and similar or better fingerling growth as the fishmeal-only feed, including fingerlings of a trout strain that are highly selective feeders. The amino acid and fatty acid composition of fingerling tissues at the end of the experiment was mostly indistinguishable among the three feed treatments. In addition, the tissue composition of fingerlings, such as the EAA : NEAA ratio and the amounts of SFA, MUFA, and PUFA, did not fully match the biochemical composition of their feeds, likely due in part to the capacity of freshwater salmonids for bioconversion of some amino acids into other less available amino acids. M. diluviana was therefore found to be an effective source of protein and lipid for fingerling rainbow trout and an effective substitute for marine fishmeal in trout aquafeed.

This study investigates the impacts of dietary Etlingera elatior (Jack) bud flower powder (EE) supplementation on the growth and health status of African catfish, Clarias gariepinus. Each treatment group received different formulated diets: basal diet without EE (control), basal diet + 1% EE (EE1), basal diet + 2% EE (EE2), basal diet + 3% EE (EE3), and basal diet + 4% EE (EE4). After an 8-week feeding trial, fish supplemented with dietary EE exhibited significantly improved growth performance, such as weight gain (WG; 1,251.4%–1,604.3%; p < 0.0001), specific growth rate (SGR; 2.02%–2.20%; p < 0.0001), and final weight (FW; 141.7–178.9 g; p < 0.0001) than the control group (WG: 1,192.0%, SGR: 1.98%, and FW: 136.1 g), particularly EE2 and EE3. Furthermore, EE-treated fish recorded significantly lower feed conversion rate (FCR; 1.19–1.53; p < 0.0001), viscerosomatic index (VSI; 3.40%–4.50%; p < 0.0001), and hepatosomatic index (HSI; 3.13%–4.40%; p < 0.0001) than the control (FCR: 1.59, VSI: 5.48%, and HSI: 4.75%), particularly EE2 and EE3. The EE-treated fish also had significantly higher white blood cell (WBC) count (124.6–148.6/µL; p < 0.0400), red blood cell (RBC) count (2.43–4.03 × 10³/µL; p < 0.0002), hemoglobin (HGB) concentration (6.27–7.87 g/dL; p < 0.0160), and hematocrit (HCT; 26.8%–38.7%; p < 0.0200) compared to the control (WBC count: 112.1/µL, RBC count: 2.17 ×10³/µL, HGB concentration: 5.60 g/dL, and HCT: 23.7%), with the highest being EE2 and EE3. Dietary EE diets enhanced digestive enzyme activities, including amylase (p < 0.0090), protease (p < 0.0040), and lipase (p < 0.0060), significantly (p < 0.05) than the control, where EE2 and EE3 demonstrated the highest activities. The EE supplementation also significantly improved the fish’s antioxidative responses, particularly catalase (CAT; p < 0.0100), glutathione peroxidase (GPx; p < 0.0300), and superoxide dismutase (SOD; p < 0.0100) in EE2 and EE3. Similarly, the cumulative survival rate of EE2 (66.7% ± 5.77%) and EE3 (66.7% ± 5.77%) were significantly (p < 0.0001) higher than other groups post-Edwardsiella tarda challenge. Therefore, this study findings highlighted the potential benefits of EE as a feed additive to boost the production in African catfish farming.

The purpose of this study was to investigate the adaptive strategies and compensatory growth mechanisms of juvenile Epinephelus coioides under starvation stress. The fish with an initial body weight of 8.88 ± 0.06 g were starved for 0 day (F0, control), 3 days (F3), 6 days (F6), 9 days (F9), 12 days (F12), and 15 days (F15), followed by feeding periods of 30 days, 27 days, 24 days, 21 days, 18 days, and 15 days, respectively. The results are shown as follows: (1) E. coioides could achieve complete or partial compensatory growth by improving both feeding rate and feed conversion efficiency. (2) The viscerosomatic index and the hepatosomatic index of the test fish decreased linearly with the duration of starvation (P < 0.05), while the condition factor did not significantly decrease (P > 0.05). At the end of feeding, all the physical body indicators of the test fish recovered or exceeded the control levels. (3) The lipid and glycogen contents of the test fish decreased continuously throughout the entire starvation process, with noticeable protein consumption occurring in the later stages of starvation (P < 0.05). At the end of the feeding period, apart from a significant reduction in crude lipid contents in the F12 and F15 groups compared to the control group (P < 0.05), the biochemical composition of the test fish was restored or even surpassed that of the control group. (4) The activity of digestive enzymes could be stimulated by starvation, enabling the efficient utilization of energy storage substances. In conclusion, it is advisable to limit the period of starvation for juvenile E. coioides to 12 days, which means that the ratio of starvation period to feeding period should not exceed two-thirds.

Silver carp’s (Hypophthalmichthys molitrix) traits and genetic structure are being impacted by artificial proliferation and restocking enhancement. A clear genetic background of cultured silver carp is helpful for exploitation and utilization. Limited research reported the germplasm resources of cultured silver carp. This study was conducted to investigate the genetic diversity of cultured silver carp. Two hundred thirty-three silver carps were sampled from eight cultured populations in Hubei province, and their population structures were analyzed by mitochondrial COI gene. Average contents of bases T, C, A, and G in the 659 bp COI gene sequence were 30.03%, 26.62%, 26.08% and 17.32%, respectively. And 18 haplotypes were defined from 77 variable nucleotides in COI gene. The haplotypes and nucleotide diversities were 0.604 and 0.00325, respectively. Meanwhile, the highest genetic diversity and lowest genetic diversity were detected in cultured populations from Jianli population (Hd: 0.883 and π: 0.00699) and Yaowan population (Hd: 0.186 and π: 0.00085), respectively. Pairwise fixation index (Fst) analysis revealed that the level of genetic diversity was moderate (Fst: 0.06). The genetic distance between and within populations were 0.00353 and 0.00329, respectively. And the genetic variation occurred mainly within populations (93.42%), but genetic variation between the population was only 6.58%. Therefore, moderate-level genetic diversity was observed with high haplotype diversity and low nucleotide diversity, suggesting that inbreeding should be avoided among the eight cultured populations in Hubei.