Introduction
Fishmeal and fish oil have traditionally been the primary ingredients in aquaculture feeds due to their high nutritional value. They provide a rich source of protein with a balanced profile of essential amino acids, along with good digestibility and high palatability. This is why they became key ingredients, particularly for carnivorous species, in the early stages of intensive aquaculture development (FAO, 2002).
However, with the rapid growth of aquaculture worldwide, the demand for fishmeal and fish oil has been gradually increasing, while their production has remained static. This imbalance has led to a growing reliance on marine resources which, combined with competition from other sectors for raw materials (such as the food industry), has resulted in rising prices and economic risks for producers. Additional challenges arise from environmental, ecological, ethical, and food safety considerations.
Consequently, the aquaculture sector must research and implement alternative food sources to ensure its proper development.
Alternative food sources in aquaculture
Among the main alternatives studied, plant-based raw materials stand out for their greater availability and stability of supply, as well as offering greater profitability compared to traditional ingredients, such as fishmeal and fish oil. From an environmental perspective, the use of plant-based raw materials in aquaculture feed formulation also helps reduce the impact of overfishing and promotes more sustainable production systems (Zlaugotne et al., 2022).
Despite these advantages, several technical limitations must be taken into account which restrict the complete replacement of fishmeal with plant-based ingredients: unbalanced essential amino acid profiles, the presence of antinutritional factors (phytoestrogens, protease inhibitors, antivitamins and contaminants such as mycotoxins) in some ingredients, reduced digestibility and bioavailability values, as well as physiological impacts, … (Hussain et al., 2024).
Nevertheless, many plant sources contain adequate protein levels and can be effectively incorporated into aquaculture feeds appropriate technological treatments, such as fermentation, heat treatment, or enzymatic processing, are applied to reduce antinutritional factors (Hussain et al., 2024).
Among the most notable plant ingredients used are (FAO, 2011):
- Protein sources, among which soybean meal stands out as the most widely used vegetable protein source in aquaculture. Other relevant options are rapeseed and sunflower meal.
- Plant ingredients that provide energy in the form of carbohydrates, such as wheat, corn, rice, and their by-products.
- Soybean, rapeseed, sunflower, and palm oils as an energy alternative to fish oils.
In addition to plant-based ingredients, other alternatives for the formulation of aquaculture feed include animal by-products, which have good protein concentration and allow the valorization of by-products from other industries, as well as options such as algae or insect meal. Although the most widely accepted conclusion is that a combination of different alternatives to fishmeal and oil should be chosen rather than a single replacement, the growing inclusion of plant-based ingredients in the formulation of aquaculture feed is clearly evident (Serra et al., 2024).
Mycotoxins: Presence in plant-based ingredients and consequences in aquaculture
Mycotoxins are toxic secondary metabolites produced by fungi. They have become a global problem affecting numerous agricultural products, either through direct contamination of plant materials or via consumption by livestock.
The increased use of plant ingredients in aquaculture leads to a greater risk of exposure of aquaculture species to these toxins. However, the presence of mycotoxins in aquatic systems is not limited to contaminated feed, as they can also persist as residues in water and sediments.
For example:
- Corn: In corn and its derivatives, foods commonly associated with mycotoxin contamination, a wide range of compounds have been reported, including aflatoxins, deoxynivalenol, ochratoxin A, zearalenone, T-2 toxins, fumonisins, beauvericin, moniliformin and aurofusarin (Munkvold et al., 2019).
- Rice: Similarly, the presence of various mycotoxins has been documented in rice, such as aflatoxins, deoxynivalenol, ochratoxin A, zearalenone, fumonisins, citrinin and sterigmatocystin (Tanaka et al., 2009).
- Soybeans: In soybeans and their by-products, which are the main source of protein used in aquaculture as a substitute for traditional ingredients, the presence of multiple mycotoxins has been reported, including aflatoxins, deoxynivalenol, ochratoxin A, zearalenone and T-2 toxin, among others (Chilaka et al., 2019; Oviedo et al., 2012).
- Agro-industrial by-products: The presence of mycotoxins (aflatoxins, deoxynivalenol, ochratoxin A, zearalenone, T-2 toxins, fumonisins, among others) has also been confirmed in by-products such as sugar beet pulp, grape pomace and cocoa shells (Lopes et al., 2023).
- Insect meal: The presence of mycotoxins in insect meal has been reported, attributed to contamination of the breeding substrates used in its production (Ramos et al., 2024).
- Livestock by-products: The presence of various mycotoxins in different livestock species following feed consumption has been documented, enabling their transfer to animal by-products and, subsequently, their potential entry into the food chain of aquaculture species fed with these ingredients (Andrade et al., 2025).
The presence of mycotoxins in aquatic species has harmful effects on both animal health, affecting their productivity, and human health. The main clinical signs include oxidative stress, histopathological alterations in gills and liver, behavioral changes, reduced growth, and even death. These effects vary depending on the species and production stage.
Due to their negative impact on health and production efficiency, it is necessary to implement effective strategies to manage mycotoxins, especially with the rising use of plant-based ingredients in aquaculture feeds.
Conclusion
The increasing replacement of fishmeal and fish oil with plant-based ingredients in aquaculture feed reflects the need to ensure the economic and environmental sustainability of the sector. While these raw materials offer clear advantages in terms of availability and cost, their inclusion poses technical challenges, including nutritional limitations and the risk associated with the presence of mycotoxins. In this context, the application of specific control strategies is key to maximizing the nutritional value of feed and preserving the health and productivity of aquaculture species. Effective management of the risks associated with mycotoxin contamination will help ensure the safe and efficient use of plant-based ingredients in modern aquaculture.
