I was thinking of raising my own feeder fish. Guppies maybe?
Raising your own feeder fish is a good idea for two reasons. The main reason is that feeder fish can infect the sunfish with diseases if they have any, and buying feeders from the pet store again and again is bound to expose your predator to something nasty. The second reason is that raising your own feeders is inexpensive. It costs less money over time to maintain a feeder fish tank that breeds and restores itself than it does to go buy fish over and over.
Here are some tips for your guppy breeding tank:
1. Heavily plant the tank. This way, you won't have to remove the guppy mothers when they are about to give birth. The dense plants will hide the babies and, if you do it right, 100% of the fry will be able to avoid being eaten. This saves work for you, because it means that you don't have to bother with noticing who's pregnant and who's not. You can just ignore the tank. Also, it's lower stress for the mothers, because they don't have to be chased down and netted and taken to a birthing tank.
2. Buy a mortar and pestle (I got mine from World Market for $4) and add a small amount of crushed fish flakes to your breeding tank several times a day. Guppies don't really need any special live foods for the fry; they're able to eat crushed flakes right away. That's a benefit to having livebearers. Livebearer young are larger than egglayers' young are, and can start out their lives eating larger food particles. The babies do have small stomachs, though, and will in an ideal situation constantly browse and eat food all day long. They grow the fastest this way, if their stomachs never empty. So to get the fastest and healthiest growth of fry, you have to feed the tank multiple times a day. There doesn't need to be a lot of food, but it does have to be frequent.
A perk to this method is that the frequent food discourages the parent livebearers away from eating the fry. Fish are less likely to expend the effort to chase down a small wiggly fry when their stomachs are already full.
3. Cover the intake to your filter with mesh or nylon. Yes, nylon, like as in pantyhose. It keeps the fry from being sucked up into the filter and ripped apart. I personally used a sewing needle and some fiberglass screen, but you could probably pick up some tiny scraps of netting at JoAnn Fabrics store in the scrap aisle, too. Maintenance is easier if you don't pass the needle across the diameter of the tube. Sew around the circumference of the tube instead. Those threads across the diameter of the tube get dead plant bits gunked up in them. Oh, and a note of warning: these mesh layers will need to be cleaned out just about daily because dead plant bits will accumulate on the outside of them. It takes five minutes, which seems like nothing, and if you don't do it for a few days in a row, filter flow gets reduced dramatically. So just a word of caution there.
4. Lights. Plants need lights, and baby fish need live plants. So go to Home Depot and see if you can't get some lights for cheaper than your pet store sells them. I got my 4 foot long two bulb 700 lumens 3000+ K full spectrum shop light for $30 including bulbs at Home Depot.
5. Plants. They cost a lot less on aquabid.com than they do at your local pet store. If your local pet store even carries plants. I personally like using hornwort (ceratophyllum) in my baby tanks because you can wrap it around a square PVC frame a couple times and then bury one end of the square frame in gravel, and it looks just like you have rooted plants. Except that you don't need to fertilize the substrate ever. And hornwort has a massive amount of surface area, nearly double that of other plants. The fine leaves are great for baby concealment, and they also house lots of tasty microorganisms.
Good luck

http://www.aquabid.c...n.cgi?fwguppies
Like this one: http://www.aquabid.c...pies You could breed it and feed the culls to your sunfish.

Oh, I almost forgot. Don't only feed your sunfish guppies. It needs a full, rounded diet with varied sources of food so it can get all the nutrients it needs.
Edited by Okiimiru, 17 August 2010 - 01:04 PM.