Unsuitable for Any Purpose
(The First Tank Guide)
Feeder fish really serve no legitimate purpose in the pet trade. And, honestly, I'm not coming from the "feeding live animals is cruel" camp with that statement. I have enough experience with (and knowledge of) biology and nature to know that that is not the case. However, I do understand that some people are against feeding live foods at all, and this is fine. Very few fish require live foods, and it is easy enough to avoid those particular fish if you do not believe in feeding live animals to other animals.
Why Are Feeder Fish Bad?
To meet the demands for both quantity and price on feeder fish, these fish are generally reared in unsuitable conditions.
These fish are almost always overcrowded, and this results in a number of problems such as a suppressed immune system and restricted growth.
Also, these fish are generally malnourished. Not only does this result in a number of physiological issues (again including suppressed immunity and stunted growth), but this also means that the fish have little to no nutritional value to the larger fish you are feeding them to. i.e. You could be feeding your fish a lot of feeder fish, and still effectively starving him to death!
Further, since their immune systems are suppressed, these fish are often disease-ridden, and one of the best ways to transfer disease from one fish to another is to have a fish eat an ill fish (or a fish that just died from a particular disease).
In addition, feeder fish are likely to be carrying parasites, which could infect your other fish (depending on the parasite).
So, What Can We Do?
If you are looking for a pet, don't look at the feeder fish.
It may be tempting to get a ten or twenty cent fish, but that fish will probably be unhealthy and unlikely to survive. That "cheap" fish may end up costing you more in medications to try to get it to survive than it would have cost to just get a healthy fish in the first place.
Now, I know that many people have wonderful pet fish that started out as feeders that they "rescued," but buying these fish contributes to the production of more of them, and encourages the pet stores to stock them, furthering the problem, not solving it. Besides, you probably do not want to buy a fish just to have it die in a few days or a couple weeks... Also, if you are looking to get a fish to add to an existing tank, the feeder fish are prone to be carrying diseases and parasites, which can infect your other fish, not only resulting in the loss of your new fish, but possibly decimation of your entire fish tank.
If you are looking for a food source, there are a number of very healthy prepared foods, from flakes and pellets to frozen complete diets, and specialty foods. If you do have a fish that really needs live foods, your best option is to set up a breeding program so that you can breed healthy live foods that you raised yourself. This will give you confidence that your feeder fish are healthy and are a good food source for your predatory fish.