Beyond Growth Rates: Why do we need new indicators to measure fish health?

2 de julho de 2026

As aquaculture expands to meet the growing global demand for sustainable seafood, the sector faces an increasingly complex challenge: producing more while ensuring animal welfare, environmental responsibility, and long-term resilience. In this article, Michael Viegas explores why traditional production indicators such as growth rates and survival are no longer sufficient to fully assess fish performance, and how emerging physiological and molecular tools are opening the way towards a more predictive, welfare-oriented and sustainable approach to aquaculture management.

The limits of growth-centric metrics

In commercial settings, rapid growth is often interpreted as a sign of good health. Yet, fish may grow quickly while simultaneously accumulating skeletal deformities, chronic stress or metabolic imbalances. These hidden problems often remain undetected until they begin to compromise overall performance, reduce feeding efficiency, or increase susceptibility to disease outbreaks. At this point, sometimes irreversible, the economic and biological costs are significantly higher.

Consider chronic stress, a persistent but often invisible challenge in marine hatcheries. Fish may display acceptable growth rates while experiencing oxidative stress, impaired immune responses, or metabolic imbalance. While these conditions may not immediately translate into mortality, they gradually erode resilience. By the time mortality rises or productivity declines, the underlying physiological strain may already have been present for weeks.

If we want aquaculture to continue growing under a sustainable blue economy, performance metrics must evolve to reflect not only productivity, but also fish health and long-term resilience. Growth and survival will remain important, but they must be complemented with biochemical and metabolic health metrics that provide earlier signals of imbalance.

Looking beneath the surface

Fortunately, new tools are helping us gain insight into fish physiology. Omics approaches are increasingly used to explore fish health beyond traditional growth indicators.

Metabolomics can map thousands of small molecules in metabolism, offering a snapshot of energy use, stress, and nutritional balance. Its applications in aquaculture are diverse. In hatcheries, metabolomic profiling can help identify biomarkers of larval quality, improve broodstock management, and better understand the causes of early-stage mortality. In nutrition, it can help evaluate dietary effects, refine feeding strategies, and support the development of more sustainable feed ingredients such as single-cell proteins, animal by-products, micro- and macroalgae, and functional supplements. In disease research, resistance and clarify host–pathogen interactions, identify biomarkers of resistance, and assess treatments or vaccines. Even post-harvest, metabolomics is applied to seafood freshness, traceability, nutritional value, and monitoring of storage and processing impacts.
Lipidomics examines fatty acid and lipid profiles, showing how diets can affect inflammation, membrane structure, and bone health. Its applications in aquaculture are broad and increasingly practical. By characterizing bioactive lipids such as omega-3 PUFAs, it helps reinforce the nutritional value of aquaculture products. It also allows researchers to understand how diet and environment shape lipid metabolism, guiding feed formulation and farming conditions for improved growth and health. Beyond production, lipidomics supports sustainability by valorizing aquaculture by-products as lipid sources for food and pharmaceuticals. It further contributes to product traceability and early health monitoring through lipid biomarkers, strengthening both management and consumer confidence.
Transcriptomics and proteomics provide another layer of insight by revealing how fish respond at a molecular level to nutrition, environmental pressure, or pathogen exposure. Transcriptomics identifies which genes are activated, showing how the organism adjusts its biological strategy in response to stress or infection. Proteomics reveals the proteins that are effectively produced and operating within cells, providing a closer picture of functional immune and metabolic activity. Together, these approaches illuminate pathways linked to inflammation, cellular defense, and stress adaptation.

More importantly, they move us from reactive health management to predictive capacity, supporting smarter vaccine design, improved treatments, and the development of more robust, disease-resilient stocks.

In practical terms, these methods move us from simple outputs (“the fish grew”) to mechanistic understanding (“the fish is under oxidative stress or activating immune pathways”). This deeper insight helps anticipate whether those physiological states may ultimately compromise growth efficiency, robustness, or disease resistance.

Minimally invasive and welfare-friendly sampling

A key question remains: how do we collect meaningful data while minimizing the impact on fish welfare?

Recent advances in non- and minimally invasive sampling offer answers.

Mucus sampling: Fish skin mucus is rich in proteins, metabolites, and immune markers. It can reveal nutritional status, stress, and pathogen interactions.
Blood sampling: Even small volumes provide metabolic and immunological information. When combined with omics, blood is a minimally invasive window into fish physiology.

When coupled with omics analyses, these techniques could make routine physiological monitoring a practical management tool. Much like water quality monitoring today, they could provide farmers with early signals of health and performance, allowing for more proactive management.

Why this matters now

The case for evolving aquaculture metrics has never been stronger.

Rising feed costs and the persistent threat of disease mean that early detection of nutritional, health and welfare issues is no longer optional. It is an operational necessity that can reduce losses, improve efficiency, and minimize waste.

At the same time, societal expectations around aquaculture are shifting. Consumers and regulators increasingly expect fish to be produced responsibly, and welfare-friendly monitoring is becoming central to building trust.

Sustainability frameworks and certification schemes are also moving toward greater transparency. In this context, reporting indicators of health and resilience, rather than production tonnage alone, will become increasingly important for maintaining credibility in global seafood markets.

Toward a new definition of performance

Growth and survival will always matter as indicators of aquaculture performance. But they are not enough.

Expanding the use of predictive indicators of fish health, supported by tools such as metabolomics, lipidomics, and transcriptomics, and enabled through non- and minimally invasive sampling, offers an opportunity to better understand how fish respond to nutrition, environmental conditions, and management practices.

Rather than replacing traditional production metrics, these approaches can complement them by providing earlier insight into physiological states that may ultimately influence productivity and system stability.

As aquaculture continues to evolve, improving how we measure and interpret fish health can help producers make more informed decisions, supporting both efficient production and responsible farming practices.