i personally wouldn't mix natives w/ trops. but that's off topic.
what size is the tank? fish?
if the o and CK don't think it's food and the poly doesn't think they are food it should be fine.
didn't completely get that, oddball, but sounds good none-the-less
If you aren't sure if it'd get along with ur fish and u want one, set up a 29gallon tank for a senegal. This is a great poly starting fish, and u'll enjoy it and have a chance to try another predator fish in the tank too, such as a ctenopoma or a leaf fish, maybe even a smaller freshwater eel.