Managing mycotoxin risks in Asia-Pacific aquaculture

Asia-Pacific’s dominance in aquaculture

Global aquaculture production now accounts for 51% of the global supply of aquatic animals, surpassing fisheries for the first time — and this increase is primarily driven by growth in the Asia-Pacific region, which in 2022 produced 83.4 million metric tons (MT) of aquatic animals out of the 94.4 million MT produced worldwide.

Innovations in aquafeed formulations

The aquaculture industry’s rapid expansion is supported by innovations in aquafeed formulations, with fed aquaculture now representing 73% of total production. With fish meal and fish oil becoming scarcer and more expensive, the industry has turned to alternative protein sources, primarily plant-based ingredients.

Soybean meal is the most common plant protein used in the diets of farmed aquatic species, with inclusion rates varying across species such as Asian sea bass (25%), white-leg shrimp (35%), and pangasius catfish (42%). Other plant-based ingredients — such as wheatmeal, cornmeal and byproducts like dried distillers grains with solubles (DDGS) — are also widely used.

Risks of mycotoxin contamination

While plant-based ingredients are essential for sustainability, they bring the risk of mycotoxin contamination.

Mycotoxins are toxic compounds produced by specific fungi that grow on plants before and after harvest, especially in inadequate storage conditions. Common mycotoxins in aquafeeds include Fusarium-produced toxins (e.g., fumonisins and deoxynivalenol), as well as aflatoxins and ochratoxin A, which are produced by Aspergillus and Penicillium species during storage.

The Alltech 37+® lab offers advanced mycotoxin analysis technology such as liquid chromatography–tandem mass spectrometry (LC-MS/MS), which allows for the detection of up to 54 different mycotoxins. To assess the general risk of mycotoxin contamination, we examined the mycotoxin profiles of samples of soybean meal, DDGS, wheat and corn.

• Over 90% of DDGS samples contained Fusarium-produced mycotoxins such as fumonisins, and around 13% of these samples also contained aflatoxin B1.
• Soybean meal samples were found to contain fusaric acid, while wheat and corn samples showed high levels of type B trichothecenes (e.g., deoxynivalenol).
• Notably, emerging mycotoxins — toxins that are not yet regulated — were found in over 70% of all samples tested, highlighting the rising risk and the necessity of proper mycotoxin management.

Effects of mycotoxins on aquatic species

The presence of mycotoxins in aquafeeds poses significant risks to aquatic species. Mycotoxins can impair growth, immune response, and overall health in fish and shrimp.

Each aqua species exhibits specific sensitivities to different mycotoxins. For instance, carp are particularly vulnerable to deoxynivalenol, which has been shown to affect organ health and reduce growth performance. T-2 toxin, another common mycotoxin, can decrease feed intake and cause oxidative stress and DNA damage in common carp.

In shrimp, even low concentrations of deoxynivalenol (around 330 ppb) can lead to reduced weight gain and can impact gene expression related to antioxidative defenses. T-2 toxin and fumonisins also significantly affect shrimp health, leading to muscle deterioration, reduced growth and increased mortality. These changes not only affect the animals’ welfare but also reduce the quality and nutritional value of shrimp for consumers.

Geographical regions also vary in their susceptibility to the different mycotoxin types. For instance, storage mycotoxins such as aflatoxin and ochratoxin A are of particular concern in the Asia-Pacific region due to the high temperatures and humidity that favor their growth. These mycotoxins can reduce feed efficiency, damage vital organs like the hepatopancreas, and lower survival rates in aquatic species.

Mycotoxin prevention and mitigation strategies

Mycotoxin contamination can occur before and/or after harvest — but preventing fungal growth on crops pre-harvest has become increasingly challenging due to climate change. As a result, feed mills are now more likely to receive feedstuffs that have already been contaminated in the fields.

Fortunately, some preventive and corrective steps can be implemented at this stage to mitigate the risk of exposing fish and shrimp to mycotoxins. In fact, mycotoxin prevention and mitigation strategies along the aquafeed supply chain are primarily implemented at the feed mill level (Figure 1). The implementation of a monitoring plan at feed mills, which screen feedstuffs upon arrival, is an effective option for preventing mycotoxin contamination.

Alltech® RAPIREAD™ technology is another effective option, enabling feed producers to quickly identify and analyze up to seven key mycotoxins on-farm. Producers should also periodically send samples of their feedstuffs and final feeds for a full-spectrum analysis by a certified lab such as the Alltech 37+ lab, which can detect up to 54 different mycotoxins.

Based on the results of those analyses, feed producers can strategically supplement mycotoxin-adsorbing agents — such as those in the Mycosorb® range from Alltech — in their formulas. Some producers may decide to include these agents for prophylactic purposes without necessarily implementing a full mycotoxin-monitoring plan.

Another common feed-formulation strategy is to include mold inhibitors, such as Alltech’s Mold-Zap®, to help inhibit fungal growth and minimize the risk of contamination during storage. 

Figure 1. Recommended mycotoxin prevention and mitigation strategies for feed mills

The role of yeast cell wall extract (YCWE)

Evaluating the effectiveness of any multi-binding agent is crucial, considering that feedstuffs and aquafeeds are commonly contaminated with multiple mycotoxins.

In the literature, Mycosorb solutions are referred to as yeast cell wall extract (YCWE) and backed by decades of scientific research. Among the various detoxifying agents with multiple-mycotoxin-binding claims tested in vitro, YCWE has demonstrated the greatest efficacy, adsorbing more than 50% of deoxynivalenol, zearalenone, fumonisin B1, ochratoxin A, T-2 toxin and aflatoxin B1. YCWE has also been successfully tested in vivo in several aquatic species.

Mycosorb technology consists of insoluble carbohydrates primarily derived from the glucans in the cell walls of the Saccharomyces cerevisiae strain of yeast. Mycosorb A+® goes a step further by combining these yeast cell wall components with carbohydrate components from algae. The flexible surfaces of these active yeast cell wall components facilitate the absorption of free mycotoxins. More specifically, β-D-glucans feature spaces that align perfectly with specific mycotoxins, making them optimal binding sites. The algal components of Mycosorb A+ further enhance its binding capacity, allowing it to adsorb a broader range of mycotoxins.

Unlike clay-based mycotoxin binders, the yeast and algae components of this solution do not interact with the essential nutrients, minerals or vitamins included in the diet. Instead, they specifically bind mycotoxins in the gastrointestinal tract, inhibiting the absorption of mycotoxins into the bloodstream and their distribution to target organs. They also promote the excretion of mycotoxins through the feces. As a result, the bioavailability of these mycotoxins is minimized, as is their potential impact on animal health and performance.

For more information on how to manage the mycotoxin threat to your business, please contact our team. You can also find additional resources at knowmycotoxins.com.

About the author:

Dr. Vivi Koletsi is a global technical support specialist within Alltech’s Technology Group. She collaborates with the company’s global Aqua team regarding all technologies on the aquatic species side.   

Dr. Koletsi, a native of Ioannina, Greece, first became interested in aquaculture while completing her undergraduate studies in biology at the Aristotle University of Thessaloniki. She began focusing on fish nutrition in earnest while pursuing her master’s degree in aquaculture and marine resource management at Wageningen University & Research in the Netherlands. This interest led her to complete an internship with Alltech Coppens, during which she established a protocol to help prevent mycotoxin contamination in aqua feeds. 

Upon earning her master’s degree, Dr. Koletsi continued her mycotoxin research at the doctoral level with support from Alltech in collaboration with the Aquaculture and Fisheries Group at Wageningen University & Research. While completing her doctoral studies, Dr. Koletsi conducted trials at Alltech Coppens’ facilities while continuing laboratory work at Wageningen. Her focus was on mycotoxins’ impact on rainbow trout.  

Dr. Koletsi joined Alltech as a team member upon completion of her Ph.D. in 2023. 

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