The increasing global population has led to an increase in food demand; consequently, aquaculture is one of the food production sectors that has offered opportunities to alleviate hunger, malnutrition, and poverty. However, the development of a sustainable aquaculture industry has been hindered by the limited availability of natural resources as well as its negative impact on the surrounding environment. Hence, there is an urgent need to search for better aquacultural production systems that, despite their high productivity and profitability, utilize fewer resources such as water, energy, land, and capital in conjunction with a negligible impact on the environment. Biofloc technology (BFT) is one of the most exciting and promising sustainable aquaculture systems; it takes into account the intensive culture of aquatic species, zero water exchange, and improved water quality as a result of beneficial microbial biomass activity, which, at the same time, can be utilized as a nutritious aquaculture feed, thus lowering the costs of production. Furthermore, BFT permits the installation of integrated multi-trophic aquaculture (IMTA) systems in which the wastes of one organism are utilized as feed by another organism, without a detrimental effect on co-cultured species. This review, therefore, highlights the basics of BFT, factors associated with BFT for the successful production of aquatic species, the significance of this food production system for the sustainable production of economically important aquatic species, its economic aspects, drawbacks, limitations, and recommended management aspects for sustainable aquaculture.

Salinity and freshwater scarcity are significant challenges affecting agriculture production worldwide. Sustaining food production in arid and semi-arid regions requires innovative, efficient, and low-cost technologies. Integrated aqua-vegeculture systems (IAVS) are promising technologies for cultivating vegetable crops and rearing fish and in a closed-loop system. The system utilizes fish effluents as crop fertilizers and recycles water for increased productivity. Hence, the current study aimed to investigate the response and productivity of kale (Brassica oleracea L.) grown at different brackish water salinities in an IAVS. The greenhouse experiment followed a completely randomized design with three salinity variants (i.e., 3000, 6000, and 9000 ppm) and control (freshwater, 400 ppm) with four replicates per treatment. The study results indicated that kale grown in a greenhouse could tolerate salinity levels of up to 6000 ppm without significantly compromising the plants’ growth, yield, and nutritional composition of leaves. Likewise, rearing Oreochromis niloticus at high water salinities did not negatively impact the water quality and the growth performance, survival, and feed utilization of fish. Overall, cultivating kale and rearing O. niloticus in IAVS in water salinities reaching up to 6000 ppm could be a sustainable agricultural strategy to increase food production in regions affected by freshwater scarcity.

Salinity is one of the major abiotic stress factors that threaten crop development and sustainable food production. As a mitigation strategy, several plant growth regulators and osmoprotectants have been applied to ameliorate the negative effects of salinity stress in plants. Therefore, the current study aimed to investigate the effect of foliar applications of different concentrations of salicylic acid and proline on the growth, yield, fruit quality, and nutritional composition of cucumber crops grown under saline conditions. The three main irrigation salinity variations included electrical conductivity (EC) of 0.5 dS/m (control), EC 6.0 dS/m, and EC 12.0 dS/m. Foliar spray treatments were as follows: T1 (distilled water), T2 (1.0 mM salicylic acid), T3 (1.0 mM salicylic acid + 5.0 mM proline), and T4 (1.0 mM salicylic acid + 10 mM proline). Our results showed that foliar application of salicylic acid alone or in combination with proline under non-saline conditions improved the growth and yield of cucumber, with T4 recording the highest values. Irrigating plants with saline water (EC 6.0 and 12.0 dS/m) severely compromised cucumber's growth performance and yield, with the lowest values recorded at EC 12.0 dS/m. However, under EC 6.0 dS/m, T2 and T3 slightly ameliorated salinity stress effects regarding fruit yield, for T2, and nutritive composition of fruits, for T2 and T3. Overall, this study demonstrated that cucumber (Cucumis sativa L.) could tolerate irrigation salinity levels of up to EC 6.0 dS/m without significant detrimental effects on the growth performance, yield, and nutritional composition of fruits.

Background: Soil salinity, soil infertility, and freshwater scarcity are among the major constraints affecting agricultural ecosystems in arid and semi-arid regions of the world. Hence, there is a need to look for salt-tolerant crops and fish that can be successfully cultivated and reared respectively in such harsh environments. The implementation of biosaline integrated aquaculture-agriculture systems (IAAS) utilizing both salt-tolerant crops and fish could improve food and feed production in arid and semi-arid regions. This study, therefore, investigated the influence of salinity on the biometric traits of striped catfish (Pangasianodon hypophthalmus) and barley (Hordeum vulgare) under an IAAS. Method: The experiment followed a randomized completely block design of three salinity treatments with three replicates namely, T0: Control (freshwater mixed with chemical fertilizers), T1: 5,000 ppm, T2: 10,000 ppm, and T3: 15,000 ppm. Results: Irrigating barley with saline aquaculture wastewater at different salinities (5,000 ppm, 10,000 ppm, and 15,000 ppm) did not significantly affect the agro-morphological parameters (internode number per plant, stalk diameter, leaf number per plant, leaf area index, and leaf chlorophyll content (SPAD)) of the plants at 90 days after sowing. Moreover, the forage yield and forage quality in terms of fiber fraction, nutrient composition, and in vitro digestibility of the forage biomass were not severely affected by high salinity compared to the control (freshwater and inorganic fertilizers). Our results also showed that rearing striped catfish in saline water not exceeding 10,000 ppm did not negatively impact the growth performance (final weight, body weight gain, feed conversion ratio, specific growth rate, condition factor, and survival) and the health status of the fish. Conclusions: The integration of striped catfish and barley production in water salinities below 15,000 ppm could be a feasible alternative in safeguarding food and feed security in regions affected by soil salinity, soil infertility, and freshwater scarcity. Moreover, the salinity regime of 5,000 ppm could bring higher economic gains to farmers regarding higher crop yields (fish and forage yield).

Integrated aquaculture–agriculture systems (IAASs) offer a sustainable approach to mitigating soil salinity by utilizing aquaculture effluents for irrigation. This study evaluates the growth performance of Nile tilapia (Oreochromis niloticus) and red tilapia (Oreochromis spp.) under varying salinity conditions and investigates their effluents on intercropped wheat and sugar beet. A field experiment was conducted using a randomized block design with seven treatments: control (chemical fertilizers dissolved in freshwater) and brackish water effluents from Nile tilapia and red tilapia at salinities of 5 ppt and 10 ppt as monocultures or mixed polycultures. Fish growth parameters were assessed, while wheat and sugar beet morphological and yield traits were monitored. Statistical analyses, including correlation and principal component analysis, were performed. Red tilapia outperformed Nile tilapia at 10 ppt salinity, achieving the highest final weight (174.52 ± 0.01 g/fish) and weight gain (165.78 ± 0.01 g/fish), while the mixed polyculture at 10 ppt exhibited optimal feed conversion (FCR: 1.32 ± 0.01). Wheat growth and yield traits (plant height, stalk diameter, and panicle weight) declined significantly under salinity stress, with 10 ppt treatments reducing plant height by ~57% compared to the control. Conversely, sugar beet demonstrated resilience, with total soluble solids (TSS) increasing by 20–30% under salinity. The mixed effluent partially mitigated salinity effects on wheat at 5 ppt but not at 10 ppt. This study highlights the potential of IAAS in saline environments, demonstrating red tilapia’s adaptability and sugar beet’s resilience to salinity stress. In contrast, wheat suffered significant reductions in growth and yield.

Freshwater scarcity is a major global challenge threatening food security. Agriculture requires huge quantities of water to feed the ever-increasing human population. Sustainable irrigation techniques such as deficit drip irrigation (DDI) are warranted to increase efficiency and maximize yield. However, DDI has been reported to cause water stress in plants. The study aimed to investigate the influence of the exogenous application of salicylic acid alone (SA) or in combination with glycine betaine (GB) on the growth, yield quality, and water-use efficiency of onions under different DDI treatments (100%, 70%, and 40% field capacity (FC)). Spray treatments (sub-treatments) were as follows: T1: (distilled water), T2: (1.09 mM SA), T3: (1.09 mM SA + 25 mM GB), T4: (1.09 mM SA + 50 mM GB), and T5: (1.09 mM SA + 100 mM GB). Our results indicated that T2 slightly ameliorated the effects of water stress by improved plant heights, leaf number, pseudostem diameter, bulb quality, and nutrient content of onion bulbs, especially under the 70% FC treatment. However, T3 recorded the poorest results on leaf number, pseudostem diameter, and bulb quality under the 70% and 40% FC treatments. Generally, our results indicated that onions could tolerate moderate water stress (70% FC) without severely affecting the growth and yield of onion. In conditions where freshwater is a limiting factor, a DDI treatment of 40% FC is recommended.