Should You Feed Your Fish Live Food?
Why bother with live food? With all the various kinds of prepared flake fish food available, it would seem your fish could get a balanced diet without resorting to raising worms or flies. The answer is that you can maintain a healthy aquarium on prepared foods, but that varying the fish's diet with live food can enhance color, activity, and breeding success. Microworms. These are colorless threadlike worms called nematodes ("nema" means thread). Starter cultures can be purchased at aquarium shops or from laboratories listed in aquarium magazines. To raise the culture, put a ¼ inch to ½ inch layer of oatmeal, soaked with water so it forms a paste, in a small container - a small yogurt container will do - and add the small culture of worms. Put some tiny pinholes in the top of the container, enough to let in some air but not enough to allow the culture to dry up. Cover it. In a few days you will have a growing culture of worms.
For the very newly hatched fish, live food is absolutely necessary. Then, too, if you feed your fish food that will live in the aquarium, the chances of overfeeding become less. And if you're willing to take the time to maintain cultures of living species, it will cost less.
The maintenance, of course, is also one of the downsides – as is the yuck factor in dealing with picking the worms out of rotting culture media, and the chance that some of the creatures you raise might carry a disease or parasite into the tank.
Cheap, Easy and Clean
To feed these to your fish, take a pinch of them and drop them in the tank, or use tweezers to grab them. They will fall in a bundle to the bottom of the tank where you can watch your fish feed on them. Once again, drop in only as much as they will eat within a couple of minutes. Feed this a few times a day.
The culture will last a couple of weeks, after which it will begin to become pretty rancid, so you'll probably want to discard it, keeping a small amount in order to begin another culture.
Daphnia. The main advantage to raising these tiny crustaceans (relatives of shrimp and lobster) is that they will live in the fish tank and, until the fish eat them, will feed on waste in the tank. Fish also seem to love them. They are grown in a culture of "green water" meaning the kind of water you'd find in an algae-coated pond. To culture your own (and to ensure the culture you get is without parasites) buy a starter kit from either an aquarium shop or from any tropical fish magazine.
White worms. Smaller than earthworms, about half an inch long, a culture of white worms can be purchased and kept in a box filled with soil.
Wingless fruit flies. These are a variety of the fruit fly you find in your fruit bowl but they have no wings, or not enough wings to fly. Cultures can be purchased and raised and fish seem to move quickly after them.
Clean But Difficult
Brine shrimp. Brine shrimp are a popular species to culture. These zooplankton are also called artemia, and like shrimp, crabs and lobster, are a kind of crustacean.
The life cycle of brine shrimp can depend upon the water quality and conditions in your tank, but when you first start out, you'll usually receive a packet of dehydrated artemia cysts. In the cysts lie dormant embryos that will resume their development once they have been re-hydrated. These can remain viable for many years, providing they are kept dry and unexposed to the air – a container in the refrigerator keeps them well.
What makes these difficult to maintain is that they require a separate aquarium setup which has to be carefully maintained. If you can do it, however, these make a healthy food for both small and large fish.
Yucky and Difficult
Tubicid worms. Cultures of these sewer worms can be purchased at most fish stores. The problem is that these cultures seem more susceptible than others to bacterial diseases and parasites, which then get introduced into your tank.
Mosquito larvae. Leave water out in the spring and summer and mosquitoes, if they're around, will lay eggs on it on tiny rafts that float on the surface of the water. Place the rafts in the tank and when the eggs hatch into wriggling larvae the fish will happily eat them. The only problem with this is that if the fish don't eat them all in time, you may end up with a room full of mosquitoes.