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Tilapia, a widely farmed aquaculture fish, produces substantial waste, including viscera that contain extracellular matrix (ECM) utilized as a biomaterial for tissue regeneration applications. Extracting ECM from viscera requires a specific decellularization method, as no standardized protocol exists. This study performed three decellularization methods: sonication, orbital shaking at room temperature, and agitation at 4°C, using SDS and TX100 at concentrations of 0.1% and 0.3%. The effectiveness of each method was assessed through H&E staining, dsDNA quantification, and SEM imaging to verify cellular content removal and ECM structure preservation. Additional analyses, including ATR‐FTIR, SDS‐PAGE, protein quantification, HPLC, and detergent residue tests, were performed to examine functional groups, collagen composition, protein content, amino acid profiles, and detergent residues in the decellularized samples. The results of H&E staining showed a significant reduction in cellular components in all samples, which was confirmed through DNA quantification. Sonication with 0.3% SDS achieved the highest DNA removal rate (96.5 ± 1.1%), while SEM images revealed that agitation at 4°C with 0.3% TX100 better preserved ECM structure. Collagen was present in all samples, as confirmed by ATR‐FTIR analysis, which revealed pronounced spectral peaks in the amide I, II, III, A, and B regions. Samples treated with agitation at 4°C using 0.1% SDS exhibited the highest protein content (875 ± 15 µg/mg), whereas those treated with TX100 had lower detergent residue. Overall, the decellularization methods effectively reduced DNA content while preserving ECM structure and components, highlighting the potential of tilapia viscera as bioscaffolds and offering insights into utilizing fish waste for high‐value products. [ABSTRACT FROM AUTHOR]

Fish and seafood processing industries generate large quantities of waste, which are at the origin of several environmental, economic and social problems. However, fish waste contains high value‐added substances such as collagen, gelatin, chitin and chitosan. In Ethiopia, Arba Minch is one of the leading areas of fish production zone, and hence, everyday lot of fish waste has been generated due to this. This work has focused on the extraction and characterization of chitin and chitosan from fish wastes (Nile tilapia). The chitin and chitosan extracted were characterized by analyzing parameters such as percentage yield, moisture and ash content, solubility, degree of deacetylation, water binding capacity, fat binding capacity, intrinsic viscosity and Molecular weight (Mw). The results obtained from this study show that the yield of chitin and chitosan was 29.88 ± 0.01% and 15.87 ± 0.14%, respectively. The moisture and ash content, DD, solubility, FBC, WBC, intrinsic viscosity and Mw of the extracted chitosan were found to be 6.79 ± 0.40%, 1.22 ± 0.16%, 85.25 ± 0.28%, 94.3 ± 0.99%, 391.17 ± 0.13%, 461.34 ± 0.42%, 6.832 ± 0.0101 and 3514.730 ± 1.1 g/mol, respectively. The chitosan was then employed for apple juice clarification and the reduction in total soluble solids value from (12.67 to 9.20), titratable acidity (2.38 to 1.61) and turbidity (320.2 to 86.6) after treatments have confirmed their effectiveness on apple juice clarification. The reduction in titratable acidity has been supported by increase in pH value (3.19 to 4.29). The sensory evaluation of control juice and chitosan‐added juice samples was performed, and it has been observed that chitosan concentration of up to 0.25 g/L was well accepted by the consumers. Novelty impact statement: The current study is the first kind of attempt to analyze the different physicochemical properties of chitin and chitosan obtained from Nile tilapia fish scale wastes, from Lake Chamo, Arba Minch.It also throws light on how fish scale wastes can be converted into useful products like chitin and chitosan.The application of extracted chitosan in apple juice clarification has been successfully demonstrated in the study. [ABSTRACT FROM AUTHOR]

Food production and processing in developing countries produce a huge amount of fruit waste by‐products, which is costly and pose detrimental effects on the environment. Proteins, lipids, starch, micronutrients, bioactive compounds and dietary fibres are found in many of these fruit wastes. Among fruit wastes, citrus fruits play an important role in generating a wide range of health benefits. Citrus L. of the Rutaceae family are common fruits cultivated and consumed globally both as fresh fruits and as a juice. Citrus peel wastes (CPW) are considered the main by‐products, with an average of 60% of processed fruits; hence, CPW have a promising role in the food production industry. CPW contain high concentrations of polyphenol and essential oils, which have nutritional importance and pharmaceutical usage. There is a concern on the increasing prevalence and incidence of different fish infections and a growing interest in shifting from synthetic to natural antimicrobial agents, leading to the use of citrus peel wastes for identification of novel compounds for use as fish feed additives. Although the antimicrobial properties of EOs have been reviewed extensively, the antimicrobial properties of citrus peels oil have not been extensively discussed. In fish farming, feeding strategies that employ phytochemicals as modulators of immunological and physiological responses such as growth, antioxidant activity and gene expression have received attention. In the past years, several studies have reported positive results of using citrus peel extracts as a nutritional additive in aquafeeds. Recently, these dietary functional feed additives have been evaluated and reported to increase disease resistance and improve fish growth, animal welfare and feed utilization. This review elucidates the global production, bioactive compounds, natural sources, chemical structures, physical properties, practical applications of citrus peel wastes and extracts as a desirable and sustainable route in fish nutrition. [ABSTRACT FROM AUTHOR]

Post‐consumer food waste (FW) is a sustainable source of nutrients that could be used as aquafeed ingredient to decrease aquaculture production expenses. However, FW has a relatively low protein content. Bioprocessing can help improve the nutritional composition of FW prior to using it in aquafeed. The present study assessed the potential benefits of substituting part of juvenile Nile tilapia (Oreochromis niloticus) diets with yeast‐fermented oil‐extracted FW (FWY). Seven isonitrogenous diets (34% crude protein) were prepared, replacing the standard formulation with 0, 15, 20, 25, 30, 35 and 40% FWY. Juvenile O. niloticus (11.07 ± 0.01 g) were size sorted and stocked into 21 tanks. Each diet was randomly assigned to three replicate tanks, and fish were offered their respective diets for 6 weeks. Results suggest that up to 30% of Nile tilapia feed can be substituted with FWY without significant effect on final body weights and lengths, feed conversion ratio, specific growth rate, hepatosomatic and viscerosomatic indices, body moisture, protein and lipid content of fish. Using an inexpensive ingredient such as FWY to replace 30% of traditional aquafeed ingredients is a promising approach towards decreasing aquaculture production cost without compromising fish growth and welfare. [ABSTRACT FROM AUTHOR]

A study was conducted to assess the role of supercritical‐fluid‐extracted‐seaweed residue as a feed ingredient. 120 Labeo rohita fingerlings with an average weight of 1.83 ± 0.25 g were randomly distributed into four experimental groups and fed with diets containing seaweed waste as a dietary supplement at 0, 150, 250 and 350 g/kg of feed for a period of 60 days. The beneficial role was assessed in terms of growth‐performance, metabolic, and defense mechanism. Animals fed with seaweed‐waste showed significantly (p <.05) higher weight gain and specific growth rate (SGR). Activities of metabolic enzymes such as ALT, AST, LDH, MDH and SOD showed significantly (p <.05) lower activity in the animals fed with seaweed waste in the diet. The highest lysozyme activity was recorded in the animal's group fed with 250 g/kg of seaweed waste in the diet. Significantly, higher serum serotonin level was recorded in the animals fed with 250 g/kg of seaweed waste. It can be inferred, that the supplementation of seaweed waste as a fish feed ingredient at a 250 g/kg inclusion level improves the growth‐performance, metabolic, and defense mechanisms in fish. Inclusion of seaweed waste as feed ingredients in the aqua‐feed industry could possibly play an important role in reducing the cost of feed with added functional benefits. [ABSTRACT FROM AUTHOR]

A feeding trial was conducted to determine the optimal dietary lipid level for golden pompano Trachinotus ovatus and the effect of dietary lipid level on fish meal replacement with soy protein concentrate (SPC). Eight isonitrogenous diets were formulated to contain four lipid levels (65 g/kg, 85 g/kg, 105 g/kg and 125 g/kg) and two fish meal levels (280 g/kg and 140 g/kg) respectively. Fish (initial weight 25.2 ± 0.5 g) were fed the test diets in net pens for 7 weeks. At the same dietary fish meal level, weight gain and nitrogen retention efficiency (NRE) tended to increase, while feed intake, feed conversion ratio (FCR) and nitrogen waste tended to decrease, with elevating dietary lipid level from 65 g/kg to 105 g/kg. At the same dietary lipid level, no significant differences were found in weight gain, feed intake, FCR, NRE, condition factor, hepatosomatic index, proximate composition and nitrogen waste between fish fed the diets containing 280 g/kg and 140 g/kg fish meal. This study reveals that the optimal dietary lipid level for golden pompano should be 107 g/kg, and dietary fish meal level could be reduced to 140 g/kg by using SPC as a fish meal substitute. Elevating dietary lipid level could not significantly increase fish meal replacement level with SPC. [ABSTRACT FROM AUTHOR]

The potential use of polychaetes as feed for mud crabs and to bioremediate highly underexploited nutrient‐rich aquaculture waste was evaluated in this study. Food preference of mud crabs (Scylla olivacea) given two polychaete species, namely Namalycastis sp. (Nereididae) and Eunice reticulata, was first determined prior to elucidating the growth, survivorship and fatty acid composition of the selected polychaetes cultivated using fish culture waste (FCW). The effect of water temperature on the sexual maturation of selected polychaetes was also evaluated. Mud crabs fed on both polychaete species but a preference for Namalycastis was observed. Namalycastis fed FCW experienced lower survivorship (16.7%–58.3%) than those in control treatments of either fish feed or no feed (41.7%–100%), although statistically there were no significant differences between treatments for all three experiments. This could probably be due to mortality of FCW‐grown Namalycastis after spawning. FCW‐grown Namalycastis had significantly higher (p <.05) wet length than unfed polychaetes. Sexual maturation in Namalycastis was not affected by lowering ambient temperature from 28°C to 26°C. Compositions of arachidonic acid, eicosapentaenoic acid and docosahexaenoic acid were higher in FCW‐grown Namalycastis than unfed Namalycastis. Overall, Namalycastis can be cultured in captivity using FCW but further research is required to mass produce the polychaetes economically and sustainably. [ABSTRACT FROM AUTHOR]

Stabilized dredged sediments are used as a backfilling material to reduce construction costs and a solution to environmental protection. Therefore, the compressive strength is an important criterion to determine the stabilized dredged sediments application such as road construction, building construction, and highway construction. Using the traditional method such as empirical approach and experimental methods, the determination of compressive strength of stabilized dredged sediments is difficult due to the complexity of this composite material. In this investigation, the artificial neural network (ANN) model is introduced to forecast the compressive strength. To perform the simulation, 51 experimental datasets were collected from the literature. The dataset consists of 4 input variables (water content, cement content, air foam content, and waste fishing net content) and output variable (compressive strength). Evaluation of the models was made and compared on training dataset (70% data) and testing dataset (30% remaining data) by the criteria of Pearson's correlation coefficient (R), Mean Absolute Error (MAE), and Root Mean Square Error (RMSE). The results show that the ANN model can accurately predict the compressive strength of stabilized dredged sediments with low water content. The cement content is the most important input affecting the unconfined compressive strength. The important input affecting the unconfined compressive strength can be in the following order: cement content > air foam content > water content > waste fishing net. [ABSTRACT FROM AUTHOR]

In this study, fish farmers' management practices, occurrence, and knowledge of fish diseases in Nyeri County, Kenya, were evaluated. Fish farming management practices for small-scale farmers in Kenya have numerous challenges which have led to disease occurrence and reduced production. Moreover, the impact and association of these challenges to farmers' knowledge of fish diseases and their burden has not been fully studied. A semistructured questionnaire was used to capture farmers' biodata, fish species farmed, and farmers' management practices such as handling of nets, pond fertilization, and disposal of fish waste. Farmers' knowledge of fish diseases was based on their ability to identify independent and dependent variable indicators. Independent variables included clinical signs, decreased feeding, bulging eyes, floating on water, abdominal swelling, bulging eyes, abnormal skin color, reduced growth, and abnormal swimming with fish death as were the dependent variable. A total of 208 farmers were interviewed and included those of tilapia (134), mixed tilapia and catfish (40), catfish (22), rainbow trout, and five dams under cooperative management. Tilapia was the most kept fish species (66.8%) followed by polyculture of tilapia and catfish (20%) and rainbow trout (2%). Most respondents were male (78.5%) over 51 years of age (50%). Fifty percent of the respondents had secondary school education. There was a significant association between deaths and sharing of nets in Kieni East subcounty (p = 0.0049 , chi-square), while on-farm fish waste disposing appeared to cause higher deaths compared to burning of the waste although not statistically significant (p = 0.13). Few respondents observed decreased feed uptake (<20%) and poor growth. Fifty-seven percent of farmers reported mortalities. Fish poor growth, floating in water, and management practices in subcounties had significant effect on fish deaths. The farmers had knowledge of signs of diseased fish, but there was paucity of knowing the specific causes of disease. Farmers need to be empowered on best aquaculture husbandry to avoid disease transmission and specific fish disease signs to enhance proper reporting of disease for subsequent mitigation measures. [ABSTRACT FROM AUTHOR]

New and viable species for aquaponics and integrated multi‐trophic aquaculture (IMTA) in freshwater systems can improve yields and sustainability of aquaculture. Freshwater crayfish species such as Astacus astacus and Pontastacus leptodactylus are omnivorous feeders and considered candidates for feeding on faecal matters in existing aquaculture systems. Feeding trials were conducted to determine growth response and RNA/DNA ratio in freshwater crayfish fed fish waste. Carapace length and wet weight were measured to determine the growth response. Juvenile A. astacus was fed faeces of hybrid striped bass (Morone chrysops × Morone saxatilis) and rainbow trout (Oncorhynchus mykiss), while adult P. leptodactylus was fed with two commercial pellet diets and pikeperch (Sander lucioperca) faeces. The nutritional composition of hybrid striped bass faeces was close to optimal diet composition of A. astacus, and crayfish showed significantly higher carapace growth, weight gain and weight gain per moult as the group fed rainbow trout faeces. The growth of P. leptodactylus was significantly lower in terms of weight gain and weight gain percentage per moult for crayfish fed on pikeperch faeces. Thus, this study can recommend a co‐cultivation of hybrid striped bass and A. astacus within one system, but cannot recommend co‐cultivation of P. leptodactylus with pikeperch. Additionally, this study showed controversial results of RNA/DNA ratio and weight gain of both crayfish species. Thus, RNA/DNA ratio cannot be approved for investigations on crayfish physiological status in controlled feeding experiments if animals are fed with an inadequate diet. [ABSTRACT FROM AUTHOR]

Abstract: After filleting of tilapia, the material remaining is discarded and this waste represents about 700 g/kg of fish body volume, corresponding to carcass and viscera. These leftovers are important sources of proteins that can be used as feed in aquaculture industry by producing protein hydrolysates. In this study, two protein hydrolysates of tilapia were produced, with one (FPH1) and two (FPH2) hours of hydrolysis. The nutritional composition of the hydrolysates showed desirable levels of crude protein and essential amino acids. Electrophoresis revealed peptides ranging from 10 to 250 kDa. In addition, caseinolytic activity was recorded by zymogram. The hydrolysates were incorporated separately in experimental diets to replace fishmeal at distinct levels: 0, 40, 80 and 120 g/kg, totalizing seven diets named 0 (control), 40H1, 80H1, 120H1, 40H2, 80H2 and 120H2. A 45‐day feeding trial was carried out to evaluate the zootechnical performance of postlarvae fed these diets. In conclusion, the use of FPH2 as a substitute for fishmeal promotes better shrimp growth than FPH1 and allows higher levels of substitution. In addition, it is recommended a 60 g/kg fishmeal replacement by FPH2 to improve growth. [ABSTRACT FROM AUTHOR]

The article presents a study which aims to determine organic matter removal in a marine recirculation aquaculture systems (RAS) effluent using Abarenicola pusilla, a polychaete present in Chilean coasts and estuaries. The methodology of the study using yellowtail kingfish marine RAS sludge is mentioned. It is inferred that Abarenicola pusilla is a good possible candidate for organic matter reduction in fish waste.

In this study, we investigated the potential utility of fish skin, usually discarded during processing, as a cost-effective protein source. We evaluated the effects on juvenile black rockfish ( Sebastes schlegeli) of an 8-week feeding trial in which 0%, 5%, 10% or 20% of the casein (purified protein) in their diets was replaced with flounder skin meal. The fish that received flounder skin meal, particularly the 20% group, showed significantly higher growth performance and feeding efficiency. They had lower levels of body lipids, elevated levels of high-density lipoprotein cholesterol, and increased body and muscle protein contents. They recovered more rapidly from stress induced by anaesthesia or exposure to air. Supplementation with flounder skin meal confirms the functionality of flounder skin meal as a high collagen component of fish diets. [ABSTRACT FROM AUTHOR]

Fish farming releases extensive amounts of particulate organic waste that can be exploited by bivalves in integrated culture. We tested if mussels Mytilus galloprovincialis cultured at two depths (1 and 6 m) in a raft, moored 170 m from a fish farm had greater growth than bivalves held 550 m from the fish cages. Mussel growth was monitored monthly, covering the second phase of the culture, from thinning-out to harvest (March to November 2011). We also studied if fish solid and dissolved nutrients increased the organic content of the seston and chlorophyll- a levels near the fish cages through weekly samples. Results showed no differences in seston, chlorophyll and physiochemical characteristics of the water among rafts. Maximum growth and Condition Index ( CI) occurred during spring-summer (April-August), when mussels had access to greater food quality and quantity. Mussels cultivated close to the cages showed similar shell length, weight and CI compared with mussels distant from the fish farm. Average shell length, meat dry weight and CI at harvest were 76.31 mm, 2.51 g and 23%. Bivalves cultured distant from the fish cages displayed 26% higher biomass than the other raft at the end of the experiment. Differences in biomass were explained by the significantly higher recruitment of mussel seed observed at the raft distant from the fish cages from June to November. The lack of a significant enhancement in growth of the bivalves cultured next to finfish is discussed. [ABSTRACT FROM AUTHOR]

The lack of specific compound diets for cephalopods is limiting the industrial development of some species. In this study, four agglutinated moist diets were tested in individually reared Octopus vulgaris (979 ± 151 g) for 8 weeks. All diets were based on bogue Boops boops, accidentally reared in fish farms (aquaculture by-product), and agglutinated with alginate and calcium. One diet was based exclusively on bogue fillets, two on bogue fillets complemented with meat from two crab species ( Portunus pelagicus, Grapsus grapsus) and the last one on bogue and G. grapsus meals. As a control diet, bogue and P. pelagicus were supplied fresh on alternate days. All diets induced similar feed intake (2.1-2.6% day−1). However, the meal-based diet induced negative growth in comparison with the control and the other agglutinated diets (0.80-0.85% day−1). Higher lipid content in agglutinated diets (28-30% dw) in comparison with the control diet (16% dw) led to higher protein retention in muscle. These results underline the inadequacy of traditional meals in diets for cephalopods and that the inclusion of crab meat did not increase feeding rates and growth in O. vulgaris. The dietary fatty acid, with high levels of oleic and linoleic acid and low levels of ARA, clearly reflected in digestive gland, while only decreasing ARA and increasing EPA levels were observed in muscle, with no apparent negative effect on growth. [ABSTRACT FROM AUTHOR]

An important consideration in the design of fish farms is the fate of the resultant particulate wastes. Consequently, this study is aimed at investigating the validity of an existing near-field regulatory model that assesses the fate of particulate wastes arising from fish farms. The results from the near-field regulatory model have been compared with those from a far-field model to assess the implications of the near-field model focusing on a 1 km-by-1 km area around the fish farm and ignoring any cumulative impacts of other fish farms in the area. The study has been undertaken at a site located on the west coast of Scotland encompassing Loch Shuna and Loch Melfort, which contain eight fish farms. The far-field dispersion modelling was undertaken using a layered three-dimensional tidal model with a coupled dispersion module. This study has demonstrated a number of benefits through using a far-field model to simulate particulate waste dispersion resulting from fish farms as opposed to using a near-field model. The far-field model accounts for the spatial variability in tidal currents, which can be important in coastal areas; it also allows the impacts of multiple fish farms operating in combination to be assessed over a larger area. In addition, it was found that compared with the far-field modelling, the near-field modelling has the potential to underestimate the benthic impacts of fish farms. [ABSTRACT FROM AUTHOR]

Fish processing creates a large amount of waste of high nutrient content which, if not properly processed for use in human or animal nutrition, is likely to be deposited in the environment creating pollution problems. Waste parts from rainbow trout processing for smoking, consisting of heads, bones, tails and intestines, were used as feed ingredients for gilthead bream diets. Heads, bones and tails had similar compositions, their weighed mean indicating about 700 g kg[sup -1] moisture, 150 g kg[sup -1] protein and 110 g kg[sup -1] fat. Intestines contained higher lipid (350 g kg[sup -1]) and lower moisture (560 g kg[sup -1]) and protein content (80 g kg[sup -1]). Seasonal changes in composition indicated significant differences. Three experimental diets were formulated having the same proximate composition on a dry weight basis. The control diet (A) contained fish meal as the main protein source and fish oil as the oil supplement. In diet B part of the protein and most of lipid was provided by trout waste and in diet C most of the lipid was provided by trout intestines. Gilthead bream fingerlings of 4 g initial weight were fed to apparent satiation for 72 days, at a temperature of 20 °C, to an average final weight of 19 g. All diets were fed in a dry form. The experiment was performed in duplicate. Growth and feed utilization data were high and similar among groups. The body composition of the resulting fish did not show any difference among dietary treatments. Differences in liver lipid and fatty acid content were found between all dietary treatments. The growth and body composition data from this preliminary experiment indicated that trout waste could be used successfully as a dietary ingredient of sea bream diets. [ABSTRACT FROM AUTHOR]

Abstract The relative potential for soluble and transport losses of aquaculture waste was examined. The waste was collected at four junctures between introduction to the environment and the culmination of settlement, including samples of feed, faeces, particulate matter in the water column obtained from sediment traps, and the benthos. Organic matter was used as a model system to investigate the fate of these components because it was simple to analyse and previous research has found it to be correlated to carbon and nutrient levels in the samples. A narrow definition of each loss was considered. Soluble losses were examined by measuring change in organic matter content while the samples were in a stationary water field. The potential for transport losses was examined by determining if light and heavy fractions of a sample differed in their amount of organic matter. Faecal matter had a very high solubility potential, and lost approximately 50% of its organic matter in 12 days. No other sample had losses > 10%. The benthic samples gained organic matter while sitting in the stationary water field. There was no discernible trend to the samples' potential for transport losses. However, for all replicates combined, the smaller the proportion of the lighter fraction, the greater the difference (+) in the organic matter content between the light and heavy fractions. Thus, lighter material is the last to settle and thus more prone to be transported further afield. The implications of this study include the need for model studies to examine different types of loss and also elucidation of divergent degradation properties of each component. This study also points to a functional mechanism behind greater environmental impacts associated with poorly managed farms. [ABSTRACT FROM AUTHOR]

Abstract The apparent digestibilities (availabilities) of dry matter, protein, phosphorus and selected minerals in fish and animal by-products were determined using rainbow trout Oncorhynchus mykiss (Walbaum). Blood meal (ring-dried), feather meal and deboned fish meal had relatively high concentrations of protein, low concentrations of phosphorus and many minerals, and high digestibilities (availabilities) of these nutrients. Other animal by-products, however, had high concentrations of minerals, including phosphorus, which are associated with the bone fraction. Availabilities of manganese and zinc in the diet were reduced by the inclusion of high-ash animal by-products in the diet, whereas availabilities of potassium, sodium and copper were relatively unaffected. Dietary concentrations of bone minerals (calcium, phosphorus) and ash were inversely correlated with availabilities (% of intake) of most minerals except copper in the diet. Also, dietary concentrations of bone minerals correlated inversely with the net absorption (mg g[sup -1] diet) of zinc, manganese and magnesium in the diet. When rainbow trout were fed diets containing incremental concentrations of fish bones, the apparent availabilities of phosphorus, calcium, magnesium and iron decreased as fish bone content in the diet increased. Reducing the bone fraction of high-ash (high-phosphorus) by-product meals is therefore an essential approach to using such ingredients in low-pollution fish feeds. [ABSTRACT FROM AUTHOR]