Features of the influence of humic acids to aquaculture

Humic substances, including humic acid and fulvic acid, are a class of naturally occurring complex compounds found in soil, water and sediments. In aquatic ecosystems, humic substances have an important influence on the properties and functions of natural aquatic systems, as they play a direct role in shaping the physical and chemical environment of a water reservoir. Artificial fish farming has become necessary not only to meet the demand for edible animal proteins, but also to replenish and conserve depleted stocks and endangered fish populations. Humic substances have positive effects on many organisms, also improve some vital parameters of fish such as growth performance, stress tolerance and immune response. The fungistatic effect of humic substances on Saprolegnia parasitica, a common parasite of freshwater and marine fish, is known. Humic substances reduce the number of pathogens Vibrio harveyi and Acinetobacter in the intestines of fish. However, the addition of humic acid in high concentrations to the feed of juvenile common carp (Сyprinus carpio) caused not only improved growth and feed eating efficiency, but also had detrimental effects on gill, liver and kidney tissues. This article is a literature review that explores the advantages and disadvantages of using humic substances in aquaculture.