Do any fish eat seeds?

yup, a seed would make a tasty snack in the wild, but i wouldn't advise feeding them too all but the largest fish, who will have the digestive tract to deal with them.
 
Most seeds are pretty fatty.
If you *must* do this (and I'm not big on feeding animals things they would never encounter naturally, and aside from a tree overhanging the edge of a water source, how could that happen?) I would try and make sure that the seeds were raw and not roasted. Heat does bad things to fats.
 
AquariaCentral.com