I certainly hope you are selecting the right foods wisely particularly these feeder fish you are using for your oscar and pacu. Feeders are not always the best option. Hikari, Omega, New Life Spectrum and many other food brands should be considered. There is a fine line between nutritional value and human entertainment when you attempt live foods to your fish. Read food sticky threads in this section and then Polypterus forum next. Both forums hold a lot of food nutrition topics.