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The use of probiotic bacteria can not only enhance the nutritional utilization of fish feeds to produce more biomass but can also provide a practically “safer” alternative to the fish farming industry to reduce the abuse of antibiotics and drugs. This study investigated the possibility of colonizing Lactobacillus rhamnosus strain GG (LGG) to the intestine of Cirrhinus molitorella (mud carp) fingerling. Colonization of LGG was observed in gut tissue after 14 days of administration with a diet supplemented with 1 × 108 CFU/mL LGG. Moreover, growth performance parameters of the LGG-supplemented diet group, including relative weight gain, feed conversion ratio and feed efficiency, were found about two-fold higher than the control group after 60 days. In addition, fish fed with an LGG-supplemented diet for 60 days showed substantial resistance against the infection of pathogenic bacterial Aeromonas hydrophila, with a relative survival rate of up to 57% compared to the control group. In summary, the results indicated that LGG as dietary supplement for mud carp fingerling can enhance nutrition utilization and better protect fish against the infection of Aeromonas hydrophila. The results provide an insight to the fish farming industry, encouraging a reduction in the use of antibiotics and drugs and the production of “safer” mud carp for the market at a manageable cost.

Bivalves play important roles in the ecosystem. However, bivalve populations have suffered a global decline in recent decades. This decline has caused public concern, because bivalves provide ecosystem services and are important sources of protein and ornaments (such as pearls) that support the fishing industry in coastal zones worldwide. Microplastics are an emerging global threat for bivalves and have been commonly detected in commercial edible bivalves, including mussels, oysters and clams. To comprehensively understand impacts of microplastics on bivalves, the potential exposure pathways by which microplastics affect bivalves are reviewed. The existing scientific evidence indicates that microplastics not only directly affect the physiology of bivalves, but also indirectly affect them by changing the structure of their sedimentary habitats, impairing their food resources and delivering persistent organic pollutants. In addition, the consumption of contaminated bivalves is a main pathway of exposure to microplastics by humans, which raises potential human health concerns. An evaluation of the hazards associated with the consumption of bivalves that contain microplastics and associated toxic chemicals is urgently needed. More studies related to the effects of microplastic fibers on bivalves should be conducted, because microplastic fibers comprise the largest proportion of microplastics in the environment and bivalves.

Dioxins and dioxin-like polychlorinated biphenyls (dl-PCBs) in fish fillet counteract the health benefits of fish products. In this study, food waste was used as a protein alternative to replacing fishmeal commonly used in the commercial fish feed, aiming to cultivate Sabah grouper with acceptable levels of dioxins and dl-PCBs. The concentrations of dioxins and dl-PCBs, as well as the fish growth performance, were compared between the fish groups fed with food waste-based feed (FWBF) and commercial feed (Nanyu®, control). The results showed that the concentrations of polychlorinated dibenzo-p-dioxins (PCDDs) (1.22 pg/g dry weight (d.w.)) and non-ortho-dl-PCBs (13.0 pg/g d.w.) were significantly lower (p 0.05) in the FWBF than in the control feed (commercial feed) (PCDDs: 2.35 pg/g d.w.; non-ortho-dl-PCBs: 27.2 pg/g d.w.). The growth performance of the fish group fed with the FWBF was comparable to that fed with the control feed. There were no significant differences between the WHO

Nano/microplastics (NPs/MPs) and organic micropollutants are contaminants exerting serious threats to aquatic ecosystems, which are further aggravated through their interactions. Organic micropollutants can adsorb on the surface of NPs/MPs, enter to the digestive systems of aquatic organisms with NPs/MPs, and desorb from the surface inside the organism. Consequently, the migration behaviour of organic micropollutants is significantly affected increasing their risk to accumulate in the food chain. Therefore, understanding the adsorption interactions between NPs/MPs and organic micropollutants is critical for evaluating the fate and impact of NPs/MPs in the environment. This review article provides an overview about the role of NPs/MPs as (temporary) sinks for organic micropollutants but also as primary sources of organic micropollutants through the leaching of plastic additives. Specifically, the following aspects are discussed: adsorption/desorption mechanisms (e.g., hydrophobic partitioning interaction, surface adsorption by van der Waals forces or hydrogen bonding, and pore filling), influencing environmental factors (e.g., pH, salinity, and dissolved organic matter), leaching of plastic additives from NPs/MPs, and potential ecotoxicological effects arising from the interactions of NPs/MPs and organic micropollutants.

The objective of this research is to investigate the enzymatic activities between protein disulfide isomerase (PDI) found in animals and plants and the properties found in a commonly used Chinese medicine called Sijunzi Tang. During the investigation, PDI, which is a monomer with a molecular mass of 57.0 kDa, was used to reactivate malate dehydrogenase (MDH). However, with the interference of polycyclic aromatic hydrocarbons (PAHs), evidence indicates that such chemicals are carcinogenic, mutagenic, and toxic to humans. The enzymatic activity of PDI found in animal’s liver and plant was 1657 folds of purification; 0.284 unit/mg of enzyme activity, and 5694.4 folds of purification; 1.00 unit/mg of enzyme activity, respectively. PDI extracted in treated animal and plant tissue revealed 2.40% and 80.44% of regaining MDH enzymatic activity, respectively. Although in its initial phase of investigation, it is assumed that the properties found in Sijunzi Tang can help regain enzymatic activity in those affected by xenobiotic substances, thus, making it a potential ingredient in assisting with PDI functions.

The production and application of biochar has become increasingly popular in the past 10 years. Biochar has similar characteristics to charcoal and activated charcoal: they are all pyrogenic carbonaceous matter derived from organic carbon-rich materials and produced by pyrolysis. Studies related to the incorporation of biochar in animal feed are limited. This review summarizes major studies related to the use of biochar as a feed additive for ruminants (cattle and goats), pigs, poultry (chickens and ducks) and fish. Documented positive responses to biochar supplementation include improved growth performance, blood profiles, egg yield, ability to resist pathogens including gut pathogenic bacteria and a reduction of methane production by ruminant animals. In addition, the high sorption capacity of biochar efficiently aids the removal of pollutants and toxins from animals’ bodies as well as from farm environments. It is expected that there will be increasing use of biochar in animal farming. The potential use of biochar in the medical and human health sectors should also be explored.

The concentrations of six heavy metal/metalloids (HMs) cadmium (Cd), copper (Cu), mercury (Hg), lead (Pb), zinc (Zn), and arsenic (As) were determined in the influent, effluent, and dewatered sludge of two sewage treatment works (Yuen Long Sewage Treatment Work (YLSTW) and Shek Wu Hui Sewage Treatment Work (SWHSTW)) and river waters and sediment (Shan Pui River and Ng Tung River) within the Mai Po Ramsar site in Hong Kong SAR, China. In both STWs, Pb had the highest removal efficiencies (YLSTW 86.5 ± 19.0% to 97.3 ± 3.04%; SWHSTW 87.4 ± 12.8% to 100 ± 0.0800%). In the whole effluent toxicity test, both STWs were effective in lowering the toxicity of the effluent to zebrafish and cherry shrimp. The environmental risk assessments of these HMs on three local aquatic organisms, three species of fish, two species of crustaceans, and three species of algae, were calculated based on measured HMs concentrations in river water and sewage samples, and the predicted no-effect concentrations. Results showed that Zn concentrations in all collected samples posed potential risks to all studied aquatic organisms (average risk quotient = 445). The concentrations of Cu in the rivers posed potential risks (average risk quotient = 5.42) to all fish species. It was concluded that Zn and Hg derived from the STWs might pose potential risks to the living organisms inhabiting the Ramsar site, and Cu, Cd, Pb, and As in the rivers were originated from the two rivers and possibly other tributaries.

Water, sediment and biota (two fish and one shrimp species) samples were collected from rivers, ponds, mudflat and estuaries within the Mai Po Ramsar site in Hong Kong, China, to determine the concentrations of heavy metals/loid (HMs): cadmium (Cd), copper (Cu), mercury (Hg), lead (Pb), zinc (Zn), and arsenic (As). The mutagenicity and toxicity of water and sediment samples were evaluated using Ames test and Microtox® bioassay, respectively. Ecological risk assessments on water birds were also conducted based on HM concentrations in biota, sediment and water samples. In general, results showed that downstream of Shan Pui River and Ng Tung River had relatively higher HM concentrations (e.g. Cu: 0.992–9.49 μg/L; As: 0.342–5.83 μg/L) when compared with estuaries (Cu: 0.400–3.69 μg/L; As: 0.220–0.931 μg/L) and ponds (Cu: 0.0402–2.41 μg/L; As: 0.0501–2.10 μg/L), except Hg and Cd. On the other hand, sediment samples collected from Ng Tung River showed mutagenicity on Salmonella typhimurium tester strain TA100, while the mudflat samples had mutagenicity on tester strain TA98 used in the Ames tests. Microtox® bioassay indicated that only sediment of Ng Tung River showed acute toxicity with a 15 min half maximal effective concentration (EC50) value of 30.5%. Results of ecological risk assessments showed that grey heron (Ardea cinerea), which feeds on fish and shrimps at Shan Pui River and ponds were not at risk. However, common sandpiper (Actitis hypoleucos), which feeds at ponds were subjected to a potential health risk due to its behavior of seeking food from the sediments, especially this bird species has a small body size. This indicates juvenile birds of other species may also be affected. Remediation should be implemented to relief the potential risk of Cu and Pb, to these water birds in the Mai Po Ramsar site.

Sewage discharge could be a major source of polycyclic aromatic hydrocarbons (PAHs) in the coastal waters. Stonecutters Island and Shatin Sewage Treatment Works (SCISTW and STSTW) in Hong Kong, adopted chemically enhanced primary treatment and biological treatment, respectively. This study aimed at (1) determining the removal efficiencies of PAHs, (2) comparing the capabilities in removing PAHs, and (3) characterizing the profile of each individual PAHs, in the two sewage treatment plants (STPs). Quantification of 16 PAHs was conducted by a Gas Chromatography. The concentrations of total PAHs decreased gradually along the treatment processes (from 301±255 and 307±217ng/L to 14.9±12.1 and 63.3±54.1ng/L in STSTW and SCISTW, respectively). It was noted that STSTW was more capable in removing total PAHs than SCISTW with average total removal efficiency 94.4%±4.12% vs. 79.2%±7.48% (p

The present study aimed to formulate diets using soybean dreg to replace part of fish meal (30% and 60%) and to incorporate dietary supplement to the diets with papain to promote fish growth and decrease total cost of feed formulations for gold-lined seabream (Rhabdosargus sarba). In Experiment 1, papain was used to supplement feeds containing soybean dreg to replace part of the fish meal. In Experiment 2, bromelain and a microalgae supplement were used to supplement feeds containing soybean substitutes as a replacement of the fish meal. Results from Experiment 1 indicated that the growth performance of fish fed diets with up to 60% replacement of fishmeal with soybean residues predigested with papain were not significantly different (p > 0.05) from the control (a formula developed by Agriculture, Fisheries and Conservation Department (AFCD), which contained 49.4% fishmeal, 45.2% raw trashfish, 4.9% alpha starch and 0.5% vitamin premix). It indicated that plant protein predigested with a small amount of enzyme supplement (e.g. papain) can be used to replace fish meal in traditional fish diets, and the cost could subsequebtly be reduced. In Experiment 2, the diets containing bromelain, soybean dreg pre-digested with bromelain and supplemented with microalgae resulted in significantly better growth performance than other diet groups. Results from the present study suggested that predigesting soybean dreg with enzymes could replace up to 60% fishmeal in the moist pellets while achieving economic benefits.

Two farmed freshwater fish species Nile tilapia (Oreochromis niloticus) and jade perch (Scortum barcoo) were cultured with food waste-based diets and compared with commercial formulated control diet for a period of six months. Sixteen priority polycyclic aromatic hydrocarbons (PAHs) in the diets and cultured fish meat were tested by gas chromatography-mass spectrometry. No significant differences of ∑PAHs were observed between Nile tilapia and jade perch fed with food waste-based diets and control diet (p 0.05). However, there were significantly higher concentration of ∑PAHs in market fish compared with the same species of fish fed by food waste-based diets (p 0.05). Thus, the food waste-based diets have a potential to lower the PAH concentrations in farmed fish when compared with market fish. Based on the PAH concentrations, a human health risk assessment was made. The results indicated there were no non-cancer and very low cancer risks of consuming fish cultured with food waste-based diets at the 95th centile (Nile tilapia: hazard index (HI

There are 3,600 tonnes of food waste (FW) disposed at landfill sites daily, and the existing landfills in Hong Kong will be successively exhausted by 2020. Recycling of FW can partially ease the disposal pressure. This study aims at investigating the feasibility of using FW-based feed pellets for culturing freshwater fish, with a focus on nutritional values. Freshwater fish such as grass carp (Ctenopharyngodon idella), Nile tilapia (Oreochromis niloticus), and grey mullet (Mugil cephalus) have relatively lower dietary protein requirements than carnivorous fish. Local freshwater fish farmers prefer to use unconsumed food, agricultural by-products or leftovers from household kitchens as feed in order to reduce their operation costs. The nutritional values (essential amino acid [EAAs], crude protein, crude lipid, crude carbohydrate, total phosphorous) of Napier grass, breads, rice bran, instant noodles, soybean dregs, a commercial fish feed pellet (Jiefeng® 613) and two FW-based feed pellets were compared. FW-based feed pellets consist of meals of recycled cereal, meat, vegetable, and bone which account for 70% (w/w) of the ingredients. Formulation A (FWA) is mainly composed of 53% cereals as the major protein sources, while Formulation B (FWB) has a more balanced ratio of meat (25%) and cereal (28%). The amino acid scores of feed items for grass carp and Nile tilapia were calculated to validate whether they contained sufficient amounts of EAAs. The results demonstrated that common fish feeds are insufficient in terms of nutrient content, in particular the lysine content (except for Jiefeng® 613), crude protein (except for Jiefeng® 613 and soybean dregs) and lipids (except for the two noodle samples). In contrast, FWA and FWB contain sufficient amounts of lysine and crude protein, indicating their suitability for low trophic level fish. The result was also confirmed by the growth performance of the fish fed with different diets.

Spirulina has been proven to be an effective growth promoter for many fish species. However, most related studies have focused on herbivorous and omnivorous fish, and limited research has been conducted on carnivorous fish. In this study, spirulina (Spirulina platensis) was administrated as a feed supplement (5%, 15 % and 30 % d.w.) in fish diets, for rearing Sabah giant grouper, a popular carnivorous fish farmed in South East Asia for its desirable taste and rapid growth. The results indicated that the total weight gain in fish fed with 5% spirulina-enriched diet almost tripled (163 ± 1.3 g) of that in the control group (67.7 ± 14.0 g). The intestinal microbial communities of the fish fed with diets supplemented with different levels of S. platensis were also investigated. The Tolumonas genus showed the highest relative abundance (44.5 %±15.0 %) in the control group, whereas the Vibrio genus showed the highest relative abundance (46.5 %–66.5 %) in all fish groups fed with spirulina-enriched diets. Simpson’s diversity index showed high intestinal bacterial diversities in fish groups fed with spirulina-enriched diets. Our results demonstrated that spirulina supplementation in fish diets can modify the profile of dominant intestinal bacterial species and diversities in the fish, which affects nutrient uptake in the fish intestine.

Different types of food wastes, e.g., meats, bones, cereals, fruits, and vegetables, were collected from hotels in Hong Kong, mixed in different ratio, and processed into feed pellets (food wastes (FWs) A, B, and C) for feeding trials in aquaculture species. Grass carp fed with cereal-dominant feed (FW A) showed the best growth (in terms of specific growth rate, relative weight gain, and protein efficiency ratio), among all food waste feeds. However, the growth rates of food waste groups especially the meat product-contained feeds (FW B and FW C) were lower than the commercial feed, Jinfeng(®) 613 formulation (control). The results indicated that grass carp utilized plant proteins better than animal proteins and preferred carbohydrate as a major energy source than lipid. The high-lipid content in feed containing meat products was also a possible reason for hindering growth and resulted high body lipid. It is suggested that lipid should be removed in the preparation of food waste feed or further investigations by implementing supplements, e.g., enzymes in feed to enhance lipid or protein utilization by fish. This utilization of food waste could be an effective and practical way to deal with these wastes in this densely populated city.

Landfills, as the most common approach to disposing of municipal solid waste worldwide, disturb native ecosystems and create a need for ecological restoration. The restoration of landfill cover with biochar has shown immediate potential to improve soil microbial functions within one year. However, such characteristics could change after a longer period of time. Here, soil properties, microbial communities, and microbial functional genes related to nutrient cycling were investigated three years after the biochar amendment of the topsoil of a subtropical landfill cover. The results showed that the levels of soil organic matter, water content, total carbon (C), total nitrogen (N) and total phosphorus (P) of biochar-amended soils were higher than those of control soil. Different soil microbial community structures were observed in the biochar-amended and control soils. Nine phyla, including Proteobacteria and Acidobacteria, but not Actinobacteria or Chloroflexi, were enriched in the biochar-amended soil. Although the impact of biochar on shaping microbial communities increased after a longer period of restoration, no differences were observed in soils that were amended using different biochar:soil ratios. The abundances of functional genes related to C and N cycling decreased, whereas those of genes related to P cycling were higher in soils that received biochar amendment. This finding suggests that compared with the control soil, biochar-amended soils were less active in processes involved in C and N cycling but enhanced in processes related to P cycling. This study can serve as a reference for future ecological restoration of degraded lands using biochar.

Protein rich food waste could be used as raw materials for making fish feed pellets, which would diminish the volume of dumped waste into landfills. This study investigated the use of food waste (FW) based pellets composing of 75% food wastes derived from plant materials (cereals, fruit and vegetables) supplemented with yeast and the mixture of bromelain and papain to feed grass carp (Ctenopharyngodon idellus). Generally, improved growth performance (in terms of feed conversion ratio, protein efficiency ratio and relative weight gain) was observed in the diet groups supplemented with yeast (Saccharomyces cerevisiae). The most optimal dose was 25 g/kg yeast with enzymes (bromelain and papain, at the ratio of 1:1) and protein utilization was enhanced. Fish immunity was also stimulated, which indicated by the higher nitroblue tetrazolium and bactericidal activities. Moreover, resistance against Aeromonas hydrophilia was enhanced. It is envisaged that food waste could be widely used as feeds for culturing herbivorous fish and adding supplements such as baker’s yeast and enzymes will further enhance the feed conversion ratio and fish immunity.

The present study used commercial feeds, food waste feeds, Napier grass, and mixed feeds (food waste feed to Napier grass ratio, 1:10) to feed grass carp (Ctenopharyngodon idellus). The results indicated that grass carp fed with food waste feeds and mix feeds achieved growth performance (based on specific growth rate and feed conversion ratio) that was similar to commercial feeds (p 0.05). Concentrations of metalloid/metals in food waste feeds and polycyclic aromatic hydrocarbons (PAHs) in Napier grass were relatively higher than other types of fish feeds (p 0.05). However, most of the metalloid/metals and PAH levels in fish fed with four types of fish feeds were not significantly different (p 0.05). These findings show that food waste feeds are suitable for using in the production of fish feed and Napier grass can be served as supplemental feeds for grass carp, and hence reducing the production cost.

This study was conducted in the South East New Territories landfill in Hong Kong, with the objectives to (i) investigate the plant and animal communities' establishment and performance within 10 years after restoration and (ii) provide important information on pioneer plants species selection recommendations for restoring sanitary landfills. The studying sites were re-vegetated in 2003, with 14 pioneer plant species, including Acacia auriculiformis, A. confusa and Schefflera heptaphylla, planted. In total, four permanent quadrats (10 m × 10 m) were used for monitoring at three restored sites (sites E, N and S) and the control site C. The soil properties and plant and animal communities inside plots were investigated annually in summer and winter between 2003 and 2014. The similarity of plant and animal communities between the restored and control sites was compared using Jaccard's index. Ten years after restoration, animal and plant communities were gradually established at all sites. No animal was introduced into the restored sites in 2003; however, there were 29, 31 and 44 animal species recorded at sites E, N and S, respectively, between 2003 and 2012. Within the studying period, 38 plant species (trees: 52·63%, shrub: 21·05%, herbs: 23·68% and climber: 2·63%) were recorded in all sites and 17 (36·84%) of them were self-seeding. Exotic species, such as those from the family Acacia and Mimosaceae, were dominant at all restored sites, which implies that exotic species are more competitive and suitable to be used as pioneer species in sanitary landfill restoration. Copyright © 2015 John Wiley & Sons, Ltd.

This study aimed at using different types of food wastes (mainly containing cereal [food waste A] and meat meal [food waste B]) as major sources of protein to replace the fish meal used in fish feeds to produce quality fish. The traditional fish farming model used to culture low trophic level fish included: bighead, (Hypophthalmichthys nobilis), grass carp, (Ctenopharyngodon idellus), and mud carp, (Cirrhinus molitorella) of omnivorous chain. The results indicated that grass carp and bighead carp fed with food waste feeds were relatively free of PAHs. The results of health risk assessment showed that the fish fed with food waste feeds were safe for consumption from the PAHs perspective.

The effects of inulin and mannanoligosaccharide (MOS) on the growth performance and non-specific immunity of grass carp were studied. Two doses of prebiotic fiber with 0.2 or 2% of the fibers are being mixed into fish feed pellets. Fish growth as well as selected non-specific immune parameters of grass carp were tested in a feeding trial, which lasted for 8 weeks. Fish was fed at 2.5% body mass per day. INU02, INU2, and MOS2 significantly improved relative weight gain, specific growth rate, protein efficiency ratio, and food conversion ratio of grass carp fed with food waste-based diet. In terms of non-specific immune response, grass carp showed significant improvement in all three tested parameters (total serum immunoglobin, bactericidal activity, and anti-protease activity). Adding 2% of inulin (INU2) into food waste diets seemed to be more preferable than other supplemented experimental diets (INU02, MOS02, MOS2), as it could promote growth of grass carp as well as improving the non-specific immune systems of grass carp.

The fast growing of global aquaculture industry accompanied with increasing pressure on the supply and price of traditional feed materials (e.g., fish meal and soy bean meal). This circumstance has urged the need to search alternative sources of feed stuff. Food waste was used as feed stuff in rearing fish which possess substantial protein and lipid. Grass carp are major species reared in Hong Kong with lower nutritional requirements; it is also an ideal species for investigating the feasibility of using food waste as fish feeds for local aquaculture industry. The growth and immunity, reflected by total protein, total immunologlobulin (IgI), and nitroblue tetrazolium (NBT) activity of grass carp blood, were depressed when feeding with food waste feeds without enzymes. However, the supplementation of bromelain and papain in fish feed enhanced the efficient use of food waste by grass carp, which in turn improved the fish immunity. The present results indicated that the addition of those enzymes could enhance the feed utilization by fish and hematological parameters of grass carp, and the improvement on growth and immunity superior to the control (commercial feed) was observed with the addition of bromelain and papain supplement. Addition of 1 and 2 % mixture of bromelain and papain could significantly enhance the lipid utilization in grass carp.

South East New Territories (SENT) landfill (Phase I) was saturated with wastes and capped with a cover system to prevent rainfall infiltration and gas emission and to support plant growth. Subsequently, a revegetation program was conducted in 1997. Line transects were used for monitoring (i) the restored area (AT), (ii) the area adjacent to AT (BT) and (iii) the area outside AT, which served as control (CT). Flora and fauna diversities, plant performance (chlorophyll florescent and stomatal resistance of Acacia confusa) and soil properties were monitored during 2000–2012. There were 28, 24 and 23 plant species, and 61, 39 and 61 animal species found at AT, BT and CT during the past 13 years, respectively. The total number of plants recorded at AT fluctuated considerably, and was more stable at BT, especially CT. The results of similarity analyses showed that the plant community at AT were significantly different (P

The present study used food waste (collected from local hotels and restaurants) feed pellets in polyculture of low-trophic level fish [bighead (Aristichtys nobilis), grass carp (Ctenopharyngodon idellus), and mud carp (Cirrhina molitorella)] aiming at producing safe and quality products for local consumption. The results indicated that grass carp (hexachlorocyclohexanes (HCHs)

China's aquaculture industry is growing dramatically in recent years and now accounts for 60.5% of global aquaculture production. Fish protein is expected to play an important role in China's food security. Formulated feed has become the main diet of farmed fish. The species farmed have been diversified, and a large amount of 'trash fish' is directly used as feed or is processed into fishmeal for fish feed. The use of locally available food waste as an alternative protein source for producing fish feed has been suggested as a means of tackling the problem of sourcing safe and sustainable feed. This paper reviews the feasibility of using locally available waste materials, including fish waste, okara and food waste. Although the fishmeal derived from fish waste, okara or food waste is less nutritious than fishmeal from whole fish or soybean meal, most fish species farmed in China, such as tilapia and various Chinese carp, grow well on diets with minimal amounts of fishmeal and 40% digestible carbohydrate. It can be concluded that food waste is suitable as a component of the diet of farmed fish. However, it will be necessary to revise regulations on feed and feed ingredients to facilitate the use of food waste in the manufacture of fish feed.

The objective of this research is to investigate the enzymatic activities between protein disulfide isomerase (PDI) found in animals and plants and the properties found in a commonly used Chinese medicine called Sijunzi Tang. During the investigation, PDI, which is a monomer with a molecular mass of 57.0 kDa, was used to reactivate malate dehydrogenase (MDH). However, with the interference of polycyclic aromatic hydrocarbons (PAHs), evidence indicates that such chemicals are carcinogenic, mutagenic, and toxic to humans. The enzymatic activity of PDI found in animal's liver and plant was 1657 folds of purification; 0.284 unit/mg of enzyme activity, and 5694.4 folds of purification; 1.00 unit/mg of enzyme activity, respectively. PDI extracted in treated animal and plant tissue revealed 2.40% and 80.44% of regaining MDH enzymatic activity, respectively. Although in its initial phase of investigation, it is assumed that the properties found in Sijunzi Tang can help regain enzymatic activity in those affected by xenobiotic substances, thus, making it a potential ingredient in assisting with PDI functions.

Food waste was collected from local hotels and fish feed pellets were produced for a 6 months long field feeding trial. Three types of fish feed pellets (control diet: Jinfeng® 613 formulated feed, contains mainly fish meal, plant product and fish oil; Diet A: food waste based diet without meat and 53% cereal; Diet B: food waste based diet with 25% meat and 28% cereal) were used in polyculture fish ponds to investigate the growth of fish (grass carp, bighead and mud carp), changes in water quality and plankton density. No significant differences in the levels of nitrogen and phosphorous compounds of water body were observed between 3 fish ponds after the half-year feeding trial, while pond receiving Diet A had the highest density of plankton. The food waste combination of Diet B seems to be a better formulation in terms of the overall performance on fish growth.

Lactococcosis is prevalent on grey mullet (Mugil cephalus) in Hong Kong aquaculture resulting in serious economic loss. A compound formulation of Traditional Chinese Medicines (TCM) (modified Huanglian Jiedu decoction (HLJDD)) comprising Rhizoma coptidis, Radix scutellaria, Cortex phellodendri, Fructus gardeniae, Fructus forsythiae and Flos lonicerae japonicae (in a ratio of 3:2:2:3:3:5) were applied as feed supplements to deal with the disease. The Nitroblue tetrazolium activity in blood, bactericidal activity and total immunoglobulin in plasma were significantly enhanced after feeding 1% of this TCM for 28 days. The disease resistances to Lactococcus garvieae in 1% and 2% TCM feeding groups were significantly enhanced. In the in vitro study, the modified HLJDD also activated the plasma bactericidal activities (p

The use of traditional Chinese medicine (TCM) in aquaculture has been widely investigated. It is believed that herbal supplements could enhance the immunity and promote fish growth. The powdered TCM or its decoction can be easily applied in the form of feed supplements by direct incorporation into fish feeds and side effects are seldom found. In this study, Radix scutellaria (Rs) and Rhizoma coptidis (Rc) showed strong bacterial inhibition on Aeromonas hydrophila out of the sixteen selected herbal extracts. Four TCMs, R. scutellaria, R. coptidis, Herba andrographis (Ha), and Radix sophorae flavescentis (Rsf) were selected to form a compound formulation in the ratio of 1:1:2:3. A feeding experiment on grass carp was conducted with addition of the above TCM formulation (0.5, 1 and 2 % w/w) in the fish feed, and bactericidal activity, total protein and immunoglobulin in blood plasma, and nitroblue tetrazolium activity in the whole blood were measured. 2 % supplementation significantly improved (p

The main aim of this study was to investigate the feasibility of using soybean meal added with papain to replace half of the fishmeal used in the moist pellets (49% fishmeal and 45% trash fish) developed by the Hong Kong Agriculture, Fisheries and Conservation Department (AFCD) for culturing marine fish. Gold-lined seabream (Rhabdosargus sarba), brown spotted grouper (Epinephelus bleekeri) and pompano (Trachinotus blochii) were farmed at one of the research stations (Kat-O) of AFCD, for a period of 340 days. Results indicated that diets containing papain resulted in better fish growth (reflected by relative weight gain and feed conversion ratio) than diets without papain. In general, wet weight gain of fish depends on the amount of papain added in diet rather than the diet composition. Soybean used in conjunction with papain also contributed to a more effective growth than fish fed with the moist pellets alone. A laboratory experiment (using tanks) was conducted to study the effects of the diets on concentrations of ammonia, nitrite and nitrate in the tank water. Results showed that concentrations of ammonia and nitrate were significantly lower (p

The effects of Astragalus membranaceus and Lycium barbarum on the growth performance and non-specific immunity of grass carp and Nile tilapia were studied. Herb extracts of Chinese medicinal herbs (2 g kg−1 or 20 g kg−1) were incorporated into food waste based fish feed pellets. Fish growth and selected non-specific immune parameters of grass carp and Nile tilapia were studied in two separate feeding trials. Both grass carp and Nile tilapia fed diets of feed pellets containing 2 g kg−1 Lycium barbarum extract achieved the best relative weight gain, feed conversion ratio, specific growth rate and protein efficiency ratio among all experimental diets. Fish fed with diets containing 2 g kg−1 Lycium barbarum also resulted in significantly higher total immunoglobin, bactericidal activity and anti-protease activity; and also a lower mortality when challenged with pathogenic bacteria. On the other hand, both fish species fed with diets containing 20 g kg−1 of Astragalus membranaceus and 20 g kg−1 Lycium barbarum, resulted in significantly impaired weight gain. In addition, incorporation of 2 g kg−1 Lycium barbarum extract would be a more suitable dose for both fish species, in terms of achieving better feed conversion ratio, specific growth rate, protein digestibility, and improved non-specific immune parameters. Based on this study, it can be concluded that waste based feed pellets incorporated with Chinese medicinal herb extracts have the ability to enhance growth and immunity of fish. Therefore, the use of Chinese medicinal herbs in aquaculture should be encouraged, in order to replace certain antibiotics known to impose environmental and health effects through the discharge of aquaculture effluents.

The amount of food waste generated from modern societies is increasing, which has imposed a tremendous pressure on its treatment and disposal. Food waste should be treated as a valuable resource rather than waste, and turning it into fish feeds would be a viable alternative. This paper attempts to review the feasibility of using food waste to formulate feed pellets to culture a few freshwater fish species, such as grass carp, grey mullet, and tilapia, under polyculture mode (growing different species in the same pond). These species occupy different ecological niches, with different feeding modes (i.e., herbivorous, filter feeding, etc.), and therefore all the nutrients derived from the food waste could be efficiently recycled within the ecosystem. The problems facing environmental pollution and fish contamination; the past and present situation of inland fish culture (focusing on South China); upgrade of food waste based feed pellets by adding enzymes, vitamin-mineral premix, probiotics (yeast), prebiotics, and Chinese medicinal herbs into feeds; and potential health risks of fish cultivated by food waste based pellets are discussed, citing some local examples. It can be concluded that appropriate portions of different types of food waste could satisfy basic nutritional requirements of lower trophic level fish species such as grass carp and tilapia. Upgrading the fish pellets by adding different supplements mentioned above could further elevated the quality of feeds, leading to higher growth rates, and enhanced immunity of fish. Health risk assessments based on the major environmental contaminants (mercury, PAHs and DDTs) in fish flesh showed that fish fed food waste based pellets are safer for consumption, when compared with those fed commercial feed pellets.

China contributes to more than 60 % of the global aquaculture production, and its aquaculture industry has become one of the main players in food security. A large amount of antibiotics is believed to be used in fish cultivation for ensuring adequate production. The use of antibiotics as disease control agents and growth promoter in aquaculture in China has raised significant concerns recently because of the potential threats to human health. The extensive use of antibiotics in aquaculture may result in water and sediment contamination and the development of antibiotic resistance genes. In this review, the role of aquaculture in antibiotic contamination of the environment as well as the emerging concern of antibiotic resistance genes in China is discussed. Based on this review, it has been concluded that more information regarding the types and quantities of antibiotics used by Chinese fish farmers is required. Studies about the contribution of antibiotic usage in aquaculture to environmental levels in surface water, their potential risks on environment and human health, and the existence and spread of antibiotic resistance genes in aquaculture are needed.

The major purpose of this study was to use different types of food wastes which serve as the major sources of protein to replace the fish meal used in fish feeds to produce quality fish. Two types of food waste-based feed pellets FW A (with cereals) and FW B (with cereals and meat products) and the commercial feed Jinfeng® were used to culture fingerlings of three low-trophic-level fish species: bighead carp, grass carp, and mud carp (in the ratio of 1:3:1) for 1 year period in the Sha Tau Kok Organic Farm in Hong Kong. Heavy metal concentrations in all of the fish species fed with food waste pellets and commercial pellets in Sha Tau Kok fish ponds were all below the local and international maximum permissible levels in food. Health risk assessments indicated that human consumption of the fish fed with food waste feed pellets was safe for the Hong Kong residents. The present results revealed that recycling of food waste for cultivating low-trophic-level fish (mainly herbivores and detritus feeders) is feasible, and at the same time will ease the disposal pressure of food waste, a common problem of densely populated cities like Hong Kong.

In this study, different types of food wastes were used as the major source of protein to replace the fish meal in fish feeds to produce quality fish (polyculture of different freshwater fish). During October 2011-April 2012, the concentrations of Hg in water, suspended particulate matter, and sediment of the three experimental fish ponds located in Sha Tau Kok Organic Farm were monitored, and the results were similar to or lower than those detected in commercial fish ponds around the Pearl River Delta (PRD) region (by comparing data of previous and present studies). Health risk assessments indicated that human consumption of grass carp (Ctenopharyngodon idellus), a herbivore which fed food waste feed pellets would be safer than other fish species: mud carp (Cirrhina molitorella), bighead carp (Hypophthalmichthys nobilis), and largemouth bass (Lepomis macrochirus). Due to the lower species diversity and substantially shorter food chains of the polyculture system consisting of only three fish species, the extent of Hg biomagnification was significantly lower than other polyculture ponds around PRD. Furthermore, the use of food waste instead of fish meal (mainly consisted of contaminated trash fish) further reduced the mercury accumulation in the cultured fish.