Background Sodium chloride (NaCl) is an essential food additive used for preservation/flavor enhancement. Food processing with NaCl has higher sodium contents, raising the concern between the excess of dietary sodium as a risk factor for several health problems. Thus, there is a growing demand for alternatives to reduce sodium in processed foods. Scope and approach This systematic review comprehensively discusses how NaCl replacement can affect microbiological, sensory, and physicochemical attributes of processed fish products, besides identifying the current trend of a potential substitute. Key findings and conclusions KCl, K-lactate, CaCl2, MgCl2, SODA-LO salt microspheres were the main NaCl replacers found in smoked, restructured, fermented, read-to-eat, sushi, and fried cake fish products evaluating microbiological, physicochemical, and sensory parameters. The effectiveness of NaCl substitution is closely related to the particular characteristics of each fish product. Nevertheless, no study analyzed all quality parameters in each product, making it challenging to identify sodium substitution efficiency. KCl has higher research attention: the substitution of 25–50% of NaCl by KCl in combination with packaging conditions was enough to control microbial growth and reduce the prooxidant effect. However, the sensory quality was compromised, and adverse effects of high potassium intakes on health should be considered. Few studies analyzed the proximate composition, although seafood products have high protein and essential lipid content. Novel salt technologies as SODA-LO were identified as the current trend to lower sodium in fish products without taste impairment. Nevertheless, more studies are needed to elucidate the effects of its use on the overall quality of products.