Where does “стронга” come from?

стронга (Belarusian) comes from Polish Pstrąg, from Proto-Slavic pьstrǫgъ, from Proto-Slavic pьstrъ, from Proto-Slavic pьsrъ, from Proto-Balto-Slavic piśras, from Proto-Indo-European piḱrós, from Proto-Indo-European peyḱ- — to hew, cut out; to stitch, embroider, sting; to...

стронга (Belarusian): trout