Information on the microplastic (MPs) migration, particularly phthalate acid esters (PAEs) in packaged seafood, is limited to a few studies. The aim of this study is to follow the possible migration potential and speed of phthalates in rainbow trout (Oncorhynchus mykiss) fillets stored in vacuum packaging depending on the storage temperature, as well as to determine the polyethylene polymer detection. For this purpose, the fillets were randomly distributed as three pieces in each bag, vacuum‐packed, and stored at commonly used temperatures (+4°C and −20°C) for 3 months. On the first day of storage in fillet and packaging materials, in certain periods of storage, the phthalate content in the fillet of each temperature group was determined. It has been determined that the chemical composition of the bag used in the vacuum packaging process is affected by the temperature depending on the storage period, and different polymer types are formed in the packaged material. Ten types of PAEs including diisobutyl phthalate (DIBP), dibutylphthalate (DBP), di‐n‐pentyl phthalate (DPENP), di‐n‐hexyl phthalate (DHEXP), butylbenzylphthalate (BBP), di‐(2‐ethylhexyl)‐phthalate (DEHP), dicyclohexyl phthalate (DCHP), di‐n‐octylphthalate (DNOP), di‐iso‐nonylphthalate (DINP), and di‐isodecylphthalate (DIDP) were recorded in the packaging material and stored fillets. It was determined that the dominant PAE in the fillets were DPENP, and DEHP in the package at all temperature applications and storage periods. The findings help monitor the presence and migration of PAEs in foods and provide a motivating model for adopting the right technologies.