Magnetic water is produced when water is passed through a magnetic field with the purpose of modifying its structure. The
changes in physical and chemical properties of magnetised water affect the biological properties of the organisms. The
magnetic field can affect the growth of fish from the embryo to the adult stage. The present study evaluates the effects of
magnetic field exposure on water properties and hatchability of the eggs of African catfish (Clarias gariepinus). Water was
passed through magnetic devices of different intensities; namely: 0.10, 0.15 and 0.20 Tesla. The dissolved oxygen (mgL-1) and
pH levels were found to significantly (P ≤ 0.05) increase from 5.92 mgL-1 to 6.33 mgL-1, and from 8.03 to 8.19, respectively.
Ammonium (NH4-N mgL-1) level declined significantly (P ≤ 0.05) (0.20 mgL-1 to 0.16 mgL-1). Salinity (ppt), conductivity (uscm1), specific conductance (uscm-1) and total dissolved solids (mgL-1) also decreased after magnetization. Significant increase in
the rate of hatching was attained in water exposed to a magnetic field of 0.10, 0.15 and 0.20 T. The study demonstrated the
benefits of using magnetic devices that are simple, practical and cost-effective.