yes, you should be able to easily switch (or add to) your poly's diet to thawed frozen raw/cooked shrimp, earthworm/shrimp pellets, hikari sinking carnivore pellets, and frozen smelt/tilapia.
senegalus are some of the least picky bichirs when it comes to feeding. just be patient and the fish will come around. i primarily feed my bichirs a mix of frozen cooked shrimp, earthwork sticks, and other sinking pellets. good luck!--
--solomon