Microplastic is of growing concern to environmental and consumer health. This study aimed at quantifying MP in a relevant selection of tissues of farmed and wild salmon to establish likely indicator organs for future documentation purposes. Three analytical methods were tested for the characterization of microplastic (MP). Vibrational spectroscopy-microscopy and thermal degradation mass spectrometry were successfully applied to detect and quantify MP in the fish tissues. High-resolution mass spectrometry (HRMS-Orbitrap) was successful in quantifying phthalates and organophosphorus flame retardants indicating plastic contamination in tissues. 14 pooled samples of muscle and 14 pooled samples of liver from 70 fish were altogether analyzed. The outcomes of the present study point plastics contamination present in both wild and farmed salmon as well as wild mountain lake trout. Particles of minor dimension length 11-40 µm are most prevalent. The most frequently detected polymer types are PS, PP and PE, some of which were also detected in wild trout from remote mountain lakes. There are no observed differences between MP in liver and muscle tissues, per 100 g. Therefore, from the data of this study it is not possible to recommend one over the other for surveillance or effect studies. For monitoring purposes, muscle samples are routinely obtained, and may therefore be suitable for further investigation of the occurrence of MP in fish. Muscle samples may also be used for investigation of the correlation between exposure and uptake of MP.