Yes. Fish farming, or aquaculture, can affect water and sediment quality, habitats, biodiversity and resource use. The effects vary by species, production system, location, intensity, inputs and management; fish farming is not uniformly harmful or automatically sustainable. To judge a farm, consider both its local effects and impacts from producing the feed and other inputs it uses.
How fish farms can affect the environment
Environmental effects can arise at the farm site and elsewhere in the production chain. The table below summarizes the main pathways and what assessment needs to consider.
| Impact pathway | How an effect can arise | What to assess |
|---|---|---|
| Water and sediment | Uneaten feed, animal waste and other inputs can add nutrients and organic matter to receiving waters and sediments. | Water and sediment conditions, feeding and stocking practices, waste management, and the receiving environment. |
| Habitat and land use | Farm siting or infrastructure can alter land or aquatic habitats; some aquaculture development has involved wetland conversion. | Site sensitivity, habitat change, and effects on other local resource users. |
| Feed and other inputs | Feed, fry, energy and other inputs can carry environmental effects from upstream production into a farm’s overall footprint. | The relevant production chain, not just activity inside the farm boundary. |
| Medicines, disease and escapes | Medicines and chemicals, disease organisms or carriers, and escaped non-native or genetically changed animals can create ecological or human-health concerns. | Use of medicines and additives, disease controls, escape prevention, and potential effects on biodiversity and fisheries. |
| Resource use and local trade-offs | Farms may use water, land, seed, feed and energy, and may compete or interact with fisheries, navigation, agriculture and other activities. | Local environmental capacity, existing users, and planning and governance. |
These are potential impact pathways, not a claim that every farm causes every effect. FAO’s environmental assessment framework identifies water and sediment quality, habitat and land-use change, chemical and medicine effects, disease releases, escapes, biodiversity and fisheries impacts among the issues to consider.
Why effects differ from farm to farm
A farm’s effects depend partly on whether the local environment can provide the resources it needs and disperse or absorb its wastes. Production intensity, feed and stocking decisions, site conditions, species, and the effectiveness of monitoring and governance also matter. A problem at one site does not establish the impact of every farm, and a system label alone does not show whether a particular operation is well managed.
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Production scale is relevant context, but it is not a footprint measure: FAO reported that global aquaculture production of aquatic animals passed 100 million tonnes for the first time in 2024. That figure describes production, not the environmental impact of an individual farm or the sector as a whole.
Why the farm boundary is not enough
Some impacts occur before fish reach a farm. A 2025 life-cycle assessment of selected farmed fish in Greece—gilthead seabream, European seabass, meagre and red seabream—found that feed and fry production contributed significantly in most assessed impact categories, while rearing was the leading contributor to eutrophication in that study. The assessment concerned its stated Greek production-chain scope; it is an example, not a global average or a result that can be assumed for other species, countries or methods.
This is why comparisons should specify what is being measured. A system that recycles water may reduce some local effects, yet a broader assessment may also need to account for feed, fry, energy and other upstream inputs. FAO’s regional review describes lower impacts from closed systems that recycle water, organic matter and nutrients in some cases; it does not establish that every closed system has a lower total life-cycle impact.
How impacts can be reduced or managed
- Assess the site and its capacity. Consider receiving-water and sediment conditions, habitat, land use, resource availability and other local users before locating or expanding a farm.
- Manage feed, stocking and waste. Avoid unnecessary feed loss, match stocking and feeding to the system, and use waste treatment or recycling suited to the production method. Water-quality pressures can also involve polluted source water, overstocking and harmful algal blooms, so feeding changes alone may not address every cause.
- Monitor the effects that matter locally. Monitoring should be matched to the system and its likely impacts, including water and sediments, medicines, disease, escapes and habitat change. A water-quality test kit may help assess selected parameters in a pond or tank, but users need to choose one for their system and monitoring purpose; testing is not a complete solution to aquaculture impacts.
- Use medicines and additives carefully. Apply them under applicable rules and qualified oversight. FAO guidance advises against using antibiotics to prevent disease, in part to reduce resistance risks.
- Look beyond the farm gate. Where the decision requires a broader comparison, include feed, fry, energy and other relevant upstream inputs rather than treating local water quality as the whole environmental footprint.
How to compare aquaculture approaches
There is no universal best-system ranking established here. A useful comparison depends on the location, production goal and impact being assessed. Ask whether the comparison covers:
- land-based or open-water production, and how much water and nutrients are recycled;
- production intensity, waste treatment and the sensitivity of the site;
- species, feed requirements and the origin of feed and fry;
- energy use, disease controls and escape prevention; and
- monitoring, governance and effects on other local users.
FAO’s Guidelines for Sustainable Aquaculture, published on 20 January 2025, frame sustainability alongside food security, nutrition, equitable livelihoods, climate resilience and restored ecosystems. Environmental performance is therefore important, but it is one part of a broader sustainability assessment.
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