Fish meal remains one of the reference protein sources in aquaculture, but its role has shifted from a routine bulk protein source to a more strategic ingredient. Its value depends strongly on fish species, feeding habit, trophic level, life stage and farming system. In carnivorous fish, such as salmonids and many marine species, it remains useful for its digestible protein, amino acid balance, palatability, minerals, marine lipids and functional compounds, particularly in juveniles, broodstock, stressful periods and demanding feeds. In omnivorous and herbivorous fish, such as tilapias, carps and many catfish, fish meal is less indispensable and can often be largely reduced or removed when diets are properly balanced for digestible amino acids, energy, minerals and palatability. Across species, the key question is not whether fish meal is nutritionally valuable, but how much is needed, at which life stage, and whether its use is supported by performance, health, product quality, environmental and economic outcomes (Tacon et al., 2008; FAO, 2025; Glencross et al., 2024b).
Salmonids
In salmonids, particularly Atlantic salmon and rainbow trout, fish meal has historically been a benchmark protein source because its amino acid profile, digestibility, palatability and mineral supply suit fast-growing carnivorous fish. It can support feed intake, growth, feed efficiency and nutrient retention, especially in juveniles and high-performance systems (Anderson et al., 1995; Sugiura et al., 1998; Tacon et al., 2008). However, modern salmonid feeds contain much less fish meal than earlier formulations, and high replacement levels are possible when diets combine plant proteins, processed animal proteins, single-cell proteins, insect meals, crystalline amino acids, suitable lipid sources and functional additives (Kaushik et al., 2008; FAO, 2025; Glencross et al., 2024b).
The health effects of reducing fish meal depend on the replacement strategy. Well-balanced low-fishmeal diets can maintain growth and feed conversion, whereas poorly formulated diets may reduce palatability, impair gut integrity, alter microbiota or increase sensitivity to stress and disease, particularly when high levels of some plant protein sources are used (Aragão et al., 2022; Dhar et al., 2024). Fish meal may therefore remain useful in diets for fry, smolts, stressful periods or formulations based on less attractive alternative ingredients.
For product quality, fish meal contributes high-quality protein and some marine nutrients, but salmonid flesh fatty acid profile is more strongly influenced by fish oil and other lipid sources. Replacing fish meal alone does not necessarily reduce flesh n-3 fatty acids, whereas replacing both fish meal and fish oil can lower EPA and DHA unless alternative marine or algal lipid sources are used. From an environmental and economic standpoint, reducing fish meal has lowered dependence on wild marine resources, but complete removal is not always the most efficient option if it impairs feed efficiency or requires costly alternative ingredients (Kaushik et al., 2008; Aragão et al., 2022; FAO, 2025; Glencross et al., 2024b).
Marine carnivorous fish
Marine carnivorous fish, such as European seabass, gilthead seabream, red seabream and yellowtail, have traditionally received diets with relatively high fish meal levels. Fish meal is valuable in these species because it improves feed intake, provides digestible amino acids and minerals, and supports growth in juveniles and demanding production stages (Nengas et al., 1995; Kaushik et al., 2004; Tacon et al., 2008). However, several marine carnivores can tolerate substantial fish meal replacement when alternative proteins are combined and diets are balanced for amino acids, phosphorus, energy and palatability (Kaushik et al., 2004; Kaushik et al., 2008; Glencross et al., 2024b).
In European seabass, almost total replacement of fish meal by plant protein sources was shown to be technically possible, but only with careful formulation rather than simple substitution by one plant ingredient (Kaushik et al., 2004). This remains the main lesson for marine carnivores: performance can be maintained with low-fishmeal diets only when the nutritional, sensory and functional roles of fish meal are compensated. Diets based heavily on alternative proteins may affect gut morphology, immune status, oxidative balance or nutrient digestibility if antinutritional factors, amino acid deficiencies or palatability limitations are not controlled (Aragão et al., 2022; Dhar et al., 2024).
Fish meal is not the only determinant of fillet quality. Low-fishmeal diets may modify fillet composition, mineral deposition or sensory traits depending on the alternative ingredients used, while the n-3 fatty acid profile depends mainly on dietary lipid sources. Economically, fish meal may remain useful in high-value juveniles, broodstock or premium diets, but feeds for the grow-out phase increasingly rely on combinations of alternative ingredients and targeted fish meal inclusion (Kaushik et al., 2008; Glencross et al., 2024b).
Omnivorous and herbivorous fish
Tilapias
Tilapias are omnivorous fish and are much less dependent on fish meal than salmonids or marine carnivores. In intensive feeds, fish meal can improve palatability, protein quality and early growth, particularly in fry and fingerlings, but feeds for the grow-out phase can often contain little or no fish meal when plant proteins, animal by-products or other local protein sources are properly balanced (Tacon et al., 2008; Glencross et al., 2024b). In semi-intensive systems, natural pond productivity further reduces dependence on fish meal.
Performance responses depend mainly on the quality of replacement ingredients. Soybean meal, oilseed meals, cereal by-products, animal protein meals, insect meals, microbial proteins and local by-products can replace much or all of the fish meal when diets meet digestible amino acid and energy requirements and antinutritional factors are controlled (Aragão et al., 2022; Glencross et al., 2024b). Poorly balanced replacements may reduce growth, feed intake or feed conversion, but this reflects formulation failure rather than a strict requirement for high fish meal inclusion.
Health effects are also formulation-dependent. Moderate replacement by good-quality alternative proteins can maintain gut function and immune status, whereas excessive use of poorly processed plant ingredients may alter intestinal structure, microbiota and inflammatory responses (Aragão et al., 2022; Dhar et al., 2024). Fish meal may remain useful in early diets or when palatability and amino acid balance are limiting, but it is not normally required as a major protein source in feeds for the grow-out phase. Economically and environmentally, low-fishmeal or fishmeal-free diets are particularly relevant where affordable local plant and agricultural by-products are available (FAO, 2025; Glencross et al., 2024b).
Carps
Carps and other cyprinids are omnivorous to herbivorous fish and are among the aquaculture species least dependent on fish meal. In many semi-intensive pond systems, carps receive feeds with little or no fish meal, and their nutrition is supported by natural food, cereals, oilseed meals, brans and other plant-based ingredients (Tacon et al., 2008; Médale et al., 2009). Fish meal may improve protein quality and growth in some intensive diets, but it is rarely indispensable.
The performance value of fish meal in carp diets depends on species, life stage and culture intensity. Common carp can digest fish meal protein well, but it can also use plant proteins efficiently when diets are balanced and water temperature, digestibility and amino acid supply are considered (Kim et al., 1998). In rohu and other Indian major carps, fish meal replacement by improved plant protein sources may be possible when limiting amino acids are supplemented and ingredient quality is controlled (Mukhopadhyay, 2000).
Health and product-quality effects of fish meal in carp are not strong enough to support routine high inclusion. As with tilapia, poor-quality replacement diets may impair growth or gut condition, but well-formulated plant and local ingredients can support satisfactory performance. From an environmental and economic perspective, reducing fish meal is usually relevant because carps can use lower-trophic feed resources, natural pond productivity and locally available plant feedstuffs efficiently (Médale et al., 2009; FAO, 2025).
Catfish
Catfish include channel catfish, African catfish, pangasius and other farmed siluriforms. They are generally omnivorous or opportunistic carnivores and can use a wide range of protein sources. Fish meal can improve palatability and amino acid quality, especially in juvenile diets, but many catfish systems use low-fishmeal diets or replace fish meal with soybean meal, oilseed meals, animal by-products, blood meal, insect meals or local feed resources (Tacon et al., 2008; Glencross et al., 2024b).
Performance responses depend on species and replacement ingredient. African catfish and pangasius can often perform well with low-fishmeal diets when protein quality, energy balance and feed intake are maintained. Channel catfish diets have long relied heavily on plant protein sources, especially soybean meal, and fish meal is usually useful only when it improves performance, palatability or early growth enough to compensate for its cost. The main nutritional risks of replacement are amino acid imbalance, poor digestibility, antinutritional factors and low palatability rather than the absence of fish meal itself (Aragão et al., 2022; Dhar et al., 2024).
Fish meal has no systematic product-quality advantage in catfish. Flesh quality depends more on growth rate, lipid source, water quality, finishing diet and processing conditions. Economically, fish meal is often difficult to justify in feeds for the grow-out phase because production is usually cost-sensitive. Environmentally, the use of low-trophic and locally available feed ingredients is generally consistent with catfish feeding biology and production economics (FAO, 2025; Glencross et al., 2024b).
