OPEN DEBATE

Future Fish Feed: Beyond “Fish-Free”

By Alejandro Guelfo, 17 September 2025 | The real challenge is to feed more people with fewer resources while reducing environmental costs

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At the heart of the aquaculture sustainability debate lies a deceptively simple question: does fish farming produce more edible protein for people than it consumes from the sea? Measured by the net fish protein index or the Fish-in Fish-out ratio, the industry has already made a notable progress.

Take Atlantic salmon. In the 1990s, typical diets contained more than 40 per cent fishmeal and fish oil, meaning that it looks over three kilos of wild fish to produce a single kilo of farmed salmon. Today, thanks to the inclusion of plant proteins, legumes and algal oils, those figures have fallen dramatically. The ratio has dropped below one to one, making salmon a net contributor of fish protein.

Tilapia offers an even more striking example. In countries such as China, Egypt and Brazil, this freshwater staple is largely farmed on plant-based feeds, with minimal reliance on marine ingredients. Its feed efficiency ranks among the highest in aquaculture, and some studies suggest very low Fish-in Fish-out ratios – meaning it yields far more edible protein than it consumes from the sea. This makes tilapia a crucial contributor to food security in some of the world’s most populous nations. The picture is not without complications, however, as the industry’s heavy realiance on imported soy indirectly links it to deforestation in Brazil.

Shrimp farming shows a similar transition. Once highly dependent on fishmeal, producers in Ecuador, Vietnam and India now use a far broader mix of ingredients, from plant proteins to poultry by-products and, in the coming years, insect meals.

Over the past two decades, feed formulations and farm management practices have improved significantly, reducing dependence on wild-caught fish and lowering feed conversion ratios. Yet challenges remain: tuna ranching in the Mediterranean, Japan and Mexico still relies almost exclusively on sardines and mackerel, with feed ratios exceeding 15:1.

Peru’s anchoveta fishery, often criticized because much of its catch is destined for fishmeal, is in fact one of the most strictly managed quota systems in the world. In good years it is both sustainable and abundant, but its volatility is undeniable – the 2023 closure triggered by El Niño highlighted the risks of leaning too heavily on a single marine resource.

This net protein approach provides a far clearer way to judge whether aquaculture is truly helping to feed the world, or simply shifting the burden elsewhere. It recognizes that marine ingredients can be used responsibly and efficiently, provided sourcing is sustainable and inclusion rates are modest.

In this context, the F3 Fish Farm Challenge has emerged, aiming to accelerate the shift towards “fish-free” feeds. The competition has attracted attention and spurred innovation, but by making the absence of marine ingredients the central benchmark, it risks oversimplifying a complex debate. “Fish-free” does not always equate to sustainable: soy can be linked to deforestation, while novel feeds such as algal oils and microbial proteins remain expensive and energy-intensive at scale.

Next week, at Aquaculture Europe 2025 in Valencia, many academics and experts will be discussing how to manufacture the “fish-free feeds of the future”. Yet the real focus should be on systems that act as net producers of fish protein.

If F3 stands for Future Fish Feed, then the future should not be about erasing fish form the formula, but about designing smarter, more balanced diets – blending certified fishmeal, processing trimmings, insects, algae and responsibly sourced plant proteins. The real challenge is to feed more people with fewer resources while reducing environmental costs.

On that basis, the F3 Challenge would have greater impact if it rewarded efficiency and diversity rather than absolute purity. Only then will the “future feed” truly serve as a driver of resilience for aquaculture and global food security.

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