Table 1.
The positive and negative attributes of RAS in terms of carbon footprint compared to traditional aquaculture systems
| Positive aspects |
|---|
| Water conservation |
| RAS substantially reduce freshwater withdrawal by continuously treating and reusing water, leading to significantly lower water demand compared with flow-through or pond systems (Ebeling and Timmons, 2010, 2012; Timmons et al., 2006). Although reduced water use does not automatically translate into lower carbon emissions, improved water use efficiency can indirectly reduce energy required for large-volume water intake depending on the local hydrological context and system design. |
| Potential for lower carbon footprint per unit biomass |
| Despite sometimes higher absolute energy use or GHG emissions due to aeration, pumping, and treatment processes, RAS can exhibit a lower carbon footprint per unit of biomass produced because of their higher productivity and much lower land requirements (Brown et al., 2025; de Melo Júnior et al., 2025; Martins et al., 2010). Even when emissions per unit area are higher, total emissions may be lower when land use impacts and production intensity are considered. |
| Improved environmental control and biosecurity |
| RAS provide precise control over temperature, oxygen, and water quality, which enhances growth efficiency and reduces mortality (Badiola et al., 2018). Improved performance may reduce emissions intensity per kg of biomass produced. |
| Reduced discharge of nutrient-rich effluents |
| Because water is recirculated, effluent volume is relatively small and nutrients can be better managed or removed, lowering the risk of eutrophication compared to open systems (Lal et al., 2024). |
| Negative aspects |
| High capital investment (economically important but not directly related to carbon footprint) |
| RAS require advanced biofilters, pumps, oxygenation systems, and monitoring equipment. While this substantially increases investment costs, it does not directly influence carbon emissions (Badiola et al., 2018). It is nevertheless a critical limiting factor for adoption. particularly in low-resource settings. |
| Potentially high energy consumption |
| Depending on regional water availability and system configuration, RAS may consume more energy than extensive pond systems, especially where ponds operate with no aeration or pumping (Badiola et al., 2018). When powered by non-renewable energy sources, this can increase the carbon footprint. Renewable energy integration is therefore essential for minimizing GHG emissions. |
| High operating costs (not inherently linked to carbon footprint) |
| Continuous operation of pumps, blowers, treatment units, and monitoring systems increases operational expenses. Although these costs affect economic feasibility, their relationship with carbon emissions depends entirely on the energy source used. |
| Dependence on stable energy supply |
| RAS require uninterrupted operation of circulation and aeration systems. In regions with unstable electricity grids, backup generators (often diesel powered) may be necessary, potentially increasing emissions unless renewable alternatives are available. |
Table 2.
Key positive and negative aspects of integrated multitrophic aquaculture (IMTA)
| Positive aspects |
|---|
| Nutrient recycling |
| Reduced need for external inputs (feed, fertilizers) |
| Improved resource utilization efficiency |
| Potential reduction in carbon footprint |
| Enhanced water quality |
| Ecosystem diversification and biomitigation |
| Negative aspects |
| Complex multi-species management |
| Requirement for specialized knowledge (ecology, aquaculture, system design) |
| Need for specific environmental conditions |
| Limited scalability depending on site characteristics |
| Higher capital and infrastructure requirements |
| Potential resource competition between species |
Table 3.
Key positive and negative aspects of biofloc technology (BFT) in relation to carbon footprint
| Positive aspects |
|---|
| Reduced external feed inputs |
| Improved nutrient recycling |
| Lower water-exchange requirements |
| Reduced effluent discharge |
| Negative aspects |
| High energy demand (aeration, mixing) |
| Increased capital requirements |
| Potential GHG* generation |
| Management complexity |
Table 4.
Key positive and negative attributes of aquaponic systems regarding carbon footprint
| Positive aspects |
|---|
| Reduced external nutrient inputs |
| Improved resource utilization |
| Lower water use |
| Integrated plant fish nutrient recycling |
| Negative aspects |
| High energy demand (pumping, heating, lighting) |
| Limited production scale |
| High initial capital requirements |
| System management complexity |