I've been looking into bulk food recently, as the fish in the 210 usually go through a 12oz bag of Hikari Cichlid Gold in a month. I came across 2kg of Cichlid Gold an Amazon for $40. I bought some, and it is a legitimate ad. I received two 5lb bags of Hikari Gold, each about half full (the bags could hold 5lb of food, but there was only 1kg in each (2.2lb)). I know Polypterus can go through food rather quickly once they get larger, so I thought the link would be useful.
https://www.amazon.com/gp/product/B01LX9BJA0/ref=oh_aui_detailpage_o00_s01?ie=UTF8&psc=1
https://www.amazon.com/gp/product/B01LX9BJA0/ref=oh_aui_detailpage_o00_s01?ie=UTF8&psc=1