The available data on the effect of natural and artificial magnetic fields on fish behavior are considered. In this aspect, Elasmobranchii and Teleostei are studied more thoroughly. Elasmobranches and some teleosts are able to perceive magnetic fields via electroreceptors. Some teleosts can sense magnetic fields via sensory cells that contain crystals of biogenic magnetite. Laboratory and field studies demonstrate that magnetic fields affect fish locomotor activity and spatial distribution. The geomagnetic field can be used by fish for navigation. In addition, the effect of artificial magnetic fields and natural fluctuations of the geomagnetic field on fish embryos lead to changes in their development. It is suggested that changes in development can have an aftereffect on fish behavior.

This review covers the phenomenon of resonance-like responses of biological systems to low-frequency magnetic fields (LFMF). The historical development of this branch of magnetobiology, including the most notable biophysical models that explain the resonance-like responses of biological systems to LFMF with a specific frequency and amplitude, is given. Two groups can be distinguished among these models: one considers ion-cofactors of proteins as the primary targets for the LFMF influence, and the other regards the magnetic moments of particles in biomolecules. Attention is paid to the dependence of resonance-like LFMF effects on the cell type. A radical-pair mechanism of the magnetic field’s influence on biochemical processes is described with the example of cryptochrome. Conditions for this mechanism’s applicability to explain the biological effects of LFMF are given. A model of the influence of LFMF on radical pairs in biochemical oscillators, which can explain the frequency–amplitude efficiency windows of LFMF, is proposed.