Yea thats a good call with the crickets. If they are store bought and were raised from babies then they should be safe but crickets and other bugs can be dangerous. When i first purchased my oscars i used to love watching them feed.
So i was outside regularly looking for grubs, crickets, and what ever else would fit in there mouth. But then someone brought it to my attention the risk. He told me that say i found a cricket in my yard, i know what kind of fertilizer and chemicals i use. But, if that cricket came from someone elses yard or field then they carry what they came in contact with. Soooo.....contaminated cricket=dead oscar. So enjoy their spectacular feeding habbits, but be aware of what you are placing in the tank.