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This feasibility study investigates the potential use of shrimp shell waste derived from peeled fresh and dried shrimp as a source of calcium (Ca) to produce value-added products (VAP). Thermal treatment of the samples was carried out by calcination at temperatures ranging from 200 to 1000 °C, and the resulting products were characterized by Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD) analyses. The results show that the shrimp shell waste changes from black to white powder, with increasing temperature during the calcination of the carbon combustion, as proven in the thermogravimetric’s (TGA) weight loss profile. The percent calcium recovery increased from 29.51 to 71.47%, and the optimum calcination temperature was reached at 1000 °C for both dried (DSS 1000) and fresh (FSS 1000) shrimp shell wastes. Spectral analysis showed that the hydroxyapatite (HAp) using calcium oxide (CaO) from FSS 1000 sample corresponded to the characteristic peaks of hydroxyapatite (JCPDS No. 9001233), while HAp produced from Ca DSS 1000 was identified as carbonate hydroxyapatite (JCPDS No. 9003552). The properties and quality of the calcium element varied according to the process used to produce shrimp shell waste. Therefore, the study suggests that shrimp shell waste could be a valuable resource for calcium recovery while mitigating the negative impacts of waste disposal on the ecosystem.

Towards the sustainable aquaculture production, more recent technologies have been developed in the past few years. The application of effectives microbes (EM) in controlling water quality, the application of biofloc technology, aquamimicry, black soldier fly (BSF) as supplemental protein feed, application of triploidy, polyploidy, vaccines, probiotic and prebiotic, Internet of Things (IoT) in monitoring the water quality in the farm operation, monosex culture and neo-female application also being applied in the aquaculture operation. The developments of these recent technologies were towards achieving the sustainable aquaculture production, prevention of the disease outbreak, help in increasing the yield of crops harvested as well as towards the green environmental developments. This review paper emphasizes the most recent technologies developed in aquaculture in the past few years until these days. The developments of the new technology in aquaculture also in order to support the sustainable development goals (SDGs) proposed by the United Nation focused on SDG1 (no poverty) and SDG2 (zero hunger) from the increase of aquaculture production achieved through the recent developed technology. Ultimately, this review paper can generate new knowledge and information to the aquaculturist and aquafarmers on the new technologies and developments in aquaculture which could help benefit in the cultures operation and increase production in the near future.

•Crustaceans harbour microbial diversity and ecology.•Stages of growth contribute to the microbial diversity and ecology of crustaceans.•Environment, diet composition and storage temperature impact microbial community.•Biofloc technology and neutralized oxidized water could reduce microbial load.

Aquaculture effluent generation, an environmentally crucial process requires effective treatment. Simple methods like coagulation and flocculation are considered effective. In this study, chitosan from Black tiger shrimp, Penaeus monodon, was used to remove ammonia (NH3) and turbidity. Response surface methodology-optimised dosages (5.00, 12.50, and 20.00 mg·L−1), pH (5.00, 6.25, and 7.50), and settling times (5.00, 7.50, and 30.00 min) were applied. Water spinach, Ipomea aquatica, received an application for organic fertiliser after the nutrient status of the recovered floc was later determined. Results showed that at a dose of 16.25 mg·L−1, a pH of 7.5, and a settling time of 17.5 min, chitosan cleared 92.16% of the turbidity. After 30 min of settling, 84.42% of the NH3was eliminated at 5 mg·L−1and 7.5 pH. Both macronutrients (P, K, N, Mg, and Ca) and micronutrients (Co, Cu, Fe, Mn, Ni, Se, and Zn) are present in the newly discovered floc. Floc had safe low Pb and Ni levels. Plants treated with floc showed superior growth compared to those with commercial liquid fertiliser, confirming nutrient absorbability. Conclusively, this study provides an eco-friendly wastewater treatment method.

Biofloc formation is affected by the addition of carbon sources and the adequate aeration supply with a proper arrangement of aeration units. Apart from molasses was commonly used as carbon sources, the effect of different nitrogen types was also critically important in the biofloc formation. This study aimed to evaluate the effect of different aeration units and nitrogen types on the biofloc formation using bioflocculant-producing bacteria as inoculum. Experimental set-up was prepared with two types of aeration units (i.e.: air stone and aerotube) and three nitrogen types (i.e.: fish meal, grounded pellet and pellet). Water quality parameters, water physical appearance, biofloc volume and shrimp biomass were observed within 30 days of the study period. There were no significant difference (P ≤ 0.05) between the water quality parameters, however, biofloc volume and shrimp biomass showed a significant difference with the aeration units. Nitrogen types using pellet showed positive results with the formation of biofloc, while there was no formation of biofloc in the other treatments. Consequently, injection of bioflocculant-producing bacteria for the rapid formation of biofloc was recommended with a proper installation of aerotube units and pellet as a nitrogen type.

The environmental impacts of aquaculture wastewater and biowaste from shellfish processing have become a major challenge to aquaculture expansion and sustainability. There is need to develop measures for the wastewater treatment and proper recycling of the biowaste. In this study, dry legs of giant freshwater prawn (Macrobrachium rosenbergii) were chemically processed into chitin and chitosan for use as coagulant in the coagulation/flocculation of real aquaculture wastewater. Box-Behnken design in response surface methodology (RSM) was used to establish the optimum operating conditions of chitosan dosage, pH, and settling time for removal of turbidity and colour. Statistical models were generated for the independent variables after which the model was validated. Results showed that dry legs of M. rosenbergiiare mainly composed of minerals (76.36%) with low level of chitin (9.29%) and chitosan (7.02%). With 80% solubility and 91% degree of deacetylation (DDA), the smooth and none porous chitosan showed great potential of a good coagulant. This study recorded that dosage (5mg/L), pH (5) and settling time of 11.25minutes successfully removed 93.84% turbidity while 99.89% colour removal was achieved at 20mg/L at 7.5pH and 30minutes settling time. The high level of minerals in the legs was responsible for the low chitin and chitosan yields while high turbidity and colour removals were attributed to the solubility and DDA.

Microalgae are an important renewable source of carotenoids and polyunsaturated fatty acids (PUFAs), with strong antioxidant, anti-inflammatory, and hepatoprotective properties. In this study, indigenous microalgal strains from fresh, brackish, and marine waters of Peninsular Malaysia were isolated, purified, and cultured. The potential of microalgae as a natural source of lipids and carotenoids was studied using a screening test with Nile red fluorescence dye to examine the lipid and carotenoid contents. Of 125 microalgae strains, nine strains isolated from marine and brackish water samples (Chaetoceros gracilis, Chlorellasp., C. sorokiniana, C. vulgaris, Tisochrysis lutea, Nitzschia capitellata, Oocystella heteromucosa, Oocystis marina, and Thalassiosira weissflogii) showed high fluorescence intensities. Next, the biochemical composition of these nine strains was examined. Thalassiosira weissflogii(strain TRG10-p105) showed the highest production of n-3 PUFAs and carotenoids among the nine strains. This strain produced high levels of n-3 PUFAs, particularly eicosapentaenoic acid (EPA). In this strain, the EPA contents relative to the dry weight (DW) and total fatty acid content (10.8% and 21.4%, respectively) were considerably higher than those reported in species currently used in industrial applications, such as aquaculture. Thalassiosira weissflogiiTRG10-p105 had the highest total carotenoid content (20.2 mg g−1DW), primarily because of its high fucoxanthin content (11.5 mg g−1DW). The findings of this study indicate that T. weissflogiiTRG10-p105 can serve as a high-value microalgal strain from tropical regions that produces n-3 PUFAs and carotenoids in abundance. Because a high ammonium tolerance was observed in this strain, its large-scale production can be implemented in ammonium-rich water produced from waste products to reduce the cost of algae production.

The suitable culture condition for specific microalgae species is vitally important for their optimal growth and biochemical production. Therefore, this study emphasized on the isolation and screening of indigenous microalgae species with high growth performance from Setiu wetlands, Terengganu, Malaysia. Successfully isolated microalgae were identified based on morphological and molecular approaches using 18S rDNA technique. Microalgae were screened to identify their species with high growth performance based on optical density and Nile red fluorescence dye. Further, the effect of different salinity towards the growth performance of isolated microalgae and proximate composition including protein, lipid, and carbohydrate were identified. Out of nine microalgae strain, three species of indigenous microalgae were successfully isolated and identified known as Chlorella vulgaris, Tetraselmis chuii, and Isochrysis galbanaduring 16 days of culture period. The highest optical density was found in C. vulgaris, T. chuii, and I. galbanawith 1.228 ± 0.039 a.u, 0.758 ± 0.024 a.u and 0.853 ± 0.048 a.u, respectively. Chlorella vulgaris, T. chuii, and I. galbanawere also showed the highest specific growth rate with 0.548 μmax/day, 0.686 μmax/day and 0.478 μmax/day, respectively. Using Nile red fluorescent dye screening, C. vulgaris, T. chuiiand I. galbanaalso showed the highest fluorescence intensity of lipid, carotenoid and chlorophyll acontent. Based on these criteria, C. vulgaris, T. chuiiand I. galbanawere selected for further determination on the effect of salinity towards the growth and proximate composition of the selected microalgae. The optimum salinity level of culture medium for T. chuiiwas 40 ppt with the highest cell density (6.215 × 106cells/mL; Day 6), protein content (40.47 ± 0.51% of dry weight) and carbohydrate content (42.57 ± 0.83% of dry weight). For I. galbana,24 ppt was found to be the best culture medium in term of the highest cell density (20.58 × 106cells/mL; Day 7), and carbohydrate content (29.28 ± 0.47% of dry weight), while lipid content was highest at 40 ppt (15.68±0.58% of dry weight). For C. vulgaris, 10 ppt was the best culture medium in term of the highest cell density (31.17 × 106cells/mL) and lipid content (13.12 ± 1.12% of dry weight), while carbohydrate and protein content were highest at 0 ppt with 44.53±0.56% and 40.16±2.22% of dry weight, respectively. Overall, the variation of salinity had affected the growth and biochemical compositions of C. vulgaris, T. chuiiand I. galbana. Therefore, this study is important for the cultivation of C. vulgaris, T. chuiiand I. galbanaof different specific target by manipulating the salinity variation of culture medium that can be used as a feed in aquaculture industry.

•COVID-19 adversely affects the aquaculture sector of Malaysia.•Market demands and seafood supply chains are disrupted.•Economic stimulus packages could relieve the impacts of COVID-19.