With the volumes of transmitted information growth, the task of increasing the noise immunity and reliability of data transmission networks arises. The presence of interference such as nonlinear loss, chromatic dispersion, polarization mode dispersion, and inter-channel interference decreases the performance of fiber optical communication systems. Forward Error Correction (FEC) codes are vital in optical communication systems to achieve highly efficient and highly reliable communication. The paper presents research on a simulation model where FEC channel-coding schemes based on the Bose-Chaudhuri-Hocquenghem (BCH) cycling block code are integrated with non-return-to-zero on-off keying (NRZ-OOK) modulated wavelength division multiplexed (WDM) fiber optical communication systems. The results highlight the selection of coding parameters in the adopted FEC approach. In our paper, the BCH (255, 231), BCH (255, 223), and BCH (255, 191) FEC channel-coding schemes are chosen for integration in the NRZ-OOK modulated WDM optical transmission system. The paper shows the main advantages and drawbacks of the selected FEC coding scheme and provides a comparison of the proposed schemes based on their main feature, such as bit error ratio (BER), which were obtained through the simulations of 25 Gbit/s NRZ-OOK WDM fiber optical system. The dynamics of changes in BER was investigated using the Monte Carlo (MC) method for precise results. The paper shows that integration of FEC channel-coding schemes based on the BCH codes improves the noise immunity and reliability of the WDM Fiber Optical Communication Systems.