Abstract: This article presented a visualization method for detecting salmon-derived components in Oncorhynchus mykiss and Salmo salar, based on fluorescence-labeled loop-mediated isothermal amplification (LAMP) and recombinase polymerase amplification (RPA). The widely recognized COI gene was targeted to design and screen optimal primer sequences for isothermal amplification. The specificity and sensitivity of the isothermal amplification methods were analyzed, and the applicability of LAMP using rapid DNA extraction and magnetic bead-based DNA extraction techniques was compared. The results demonstrated that the constructed LAMP and RPA methods exhibited high specificity. The sensitivity of LAMP detection using magnetic bead-extracted DNA reached 2.99×10⁻¹ ng/μL and 5.16×10⁻³ ng/μL, respectively, whereas using rapid DNA extraction, sensitivity reached 9.42×10⁰ ng/μL and 1.13×10¹ ng/μL, respectively. Simulated mixed samples were prepared, and results showed that the sensitivity of RPA amplification for detecting Oncorhynchus mykiss and Salmo salar components reached 0.1% (w/w), while the sensitivity of visual LAMP amplification consistently reached 0.5% (w/w). Both LAMP and RPA methods met rapid detection requirements, characterized by low technical complexity, minimal equipment cost, and short detection time. Moreover, rapid DNA extraction using lysis solutions allowed the detection process to be completed within 30~40 min, making this approach an excellent choice for on-site authenticity testing of fish species in production, processing, and market circulation stages.