Risk of fish mycotoxicosis in aquaculture (review)

Modern fish aquaculture is a large-scale and rapidly developing industry of global production (FAO, 2018). In order to improve the quality of the products produced, an active search is underway for effective ways to control the safety of artificial feeds (J. Bostock et al., 2010). Based on the results of monitoring projects carried out in Argentina, Brazil, the United States, China, Korea and Central European countries (C. Pietsch et al., 2013; B.T.C. Barbosa et al., 2013; M. Greco et al., 2015; L. Pinotti et al., 2016), the situation of contamination of fish feed with mycotoxins is recognized as extremely serious both in terms of prevalence and content, and in terms of combined occurrence (I. Matejova et al., 2017; C. Pietsch, 2019). For the Russian fishery, which in recent years has become a multi-destination, specialists of academic and university science, as well as industry research institutes proposed feed rations that account for age and species characteristics of fish (J.A. Zheltov, 2006; Y.V. Sklyarov, 2008), and discussed in detail the problem of microbial contamination (I.V. Burlachenko, 2008). In the Russian Federation, mandatory requirements for compliance with quality and safety indicators have been introduced for raw materials and finished feed products (GOST 10385-2014) and a modern methodological base for mycotoxicological control has been created (GOST 31653-2012, GOST 31691-2012, GOST 32587-2013, GOST 34108-2017, GOST R 51116-2017).The purpose of this review is to update information on mycotoxin contamination of domestic raw materials for the production of aquafeeds, to generalize world data on the nature of acute action of the most occurring contaminants, as well as to analyze clinical signs, pathologic-anatomical and biochemical changes accompanying chronic fish mycotoxicosis. In recent years, we have received convincing evidence that the group of the most likely contaminants of raw ingredients - wheat, barley and corn flour, bran, sunflower cake and meal - includes T-2 toxin, deoxynivalenol, fumonisins of group B and zearalenone, related to fusariotoxins, as well as alternariol, ochratoxin A, citrinin, cyclopiazonic acid, mycophenolic acid and emodin (G.P. Kononenko et al., 2018, 2019). Analysis of world data on experimental mycotoxicoses of different age groups of common carp ( Cyprinus carpio ), channel catfish ( Ictalurus punctatus ), white Amur ( Ctenopharyngodon idellus ), Nile tilapia ( Oreochromis niloticus ), rainbow trout ( Oncorhynchus mykiss ), Atlantic salmon ( Salma salar ), shows that fusariotoxins should be considered as key risk factors and efforts should continue to refine their safe thresholds. Intoxications caused by ochratoxin A remain insufficiently studied, and the situation with regard to other possible feed contaminants is unclear. Reasonable proposals for regulation in fish feed were reported only for T-2 toxin for common carp (V.T. Galash, 1988), for deoxynivalenol - for white Amur (C. Huang et al., 2018, 2019, 2020) and Atlantic salmon (A. Bernhoft et al., 2018), for fumonisin B1 - for channel catfish (M.N. Li et al., 1994, S. Lumlertdacha et al., 1995). Data on the degree of retention of these mycotoxins in fish tissues is limited (C. Pietsch et al., 2014, 2015; A. Ananter et al., 2016), and therefore regulations on product residues have not yet been adopted. However, the search for new approaches to correctly assess the consequences of their negative effects and transmission to fish products continues, and this leaves no doubt that a solution will be found.