Best fish to breed as a food source for oscar??

Feeder fish aren't the best for oscars. You'd be better off getting them to eat a pellet, veggies, ect. Earthworms are a cheap and easy treat, but live food is the best staple food for their long term health.

To answer your question, cons would be good to do but the only prbbalem is it would take awhile to grow them to feed a good size oscar.

I'll agree w/OrionGirl on this one.

I agree with Oriongirl, too, but I don't think he's trying to breed a staple diet for his Oscars. I'm assuming he's breeding for the occasional feeder fish for them. I use feeder Ghost Shrimp every other week. I have also thought about breeding fish and throwing in a few young every few weeks, maybe once a month. It might be a good idea to breed Guppies since they are supposedly so prolific. I'd switch off and do staple/frozen foods - 1st week, staple/Ghost Shrimp - 2nd week, staple/frozen - 3rd, and finally staple/Guppies - 4th week. That would keep them on a very healthy, varied, and natual diet. This should meet all of their needs, and would not get them too used-to or spoiled on feeders. For ideas on my idea of a healthy feeding regimen, look at my tank specs at bottom. This is what I do, and it has been working great.

The other added benefit to breeding some kind of fish for feeders is to be able to witness their breeding activity without having to deal with the issue of housing them as they grow. You could always keep some or trade them if you chose to, yet you always have a snack on hand too! If you want to see some awesome breeding behavior at the same time, I'd suggest going with Convicts. Just my ideas......

I was considering the same thing but how big a tank would be needed to keep and breed a pair of cons?

I think it would be tight (but possible) in aything less than 3 foot tank, especially once you get some fry swimming around. I would think a 45 gallon "tub" would be ideal for breeding Convicts. It is 3'x15", or something like that. A 55 would be nice too....longer, but more narrow. You could make this a beautiful show tank as well.