Are black worms cultured like blood worms or tubifex worms? I've heard that blood or tubifex are cultured in sewage?? What about black worms??

Part of the confusion comes from naming convention. True blood worms are the larvae of the midge fly. They are generally red in color and look similar to mosquito larvae. These worms are generally considered OK to feed to your fish. They are found in clean water. (Though even clean water contains bad bacteria and parasites, so you are never 100% safe.)

The confusion comes with tubifex worms. These worms grow in sewage sludge with obviously a high concentration of bacteria. Many "experts" claim that they can be a carrier for both bacterial infections, and also tapeworm. Whether you believe the tapeworm theory or not is beside the point. The bacterial conditions that these worms live in is enough for me to stay away from them.

Now the confusion: Tubifex worms come in a variety of colors. The common ones are either red or black.... hense the names "blood worms" (Different from the midge fly larvae), black worms, or tubifex (technically "black worms" are a different species, but for purposes of this discussion, they will be lumped together with tubifex). I've heard some people say that the black variety does not live in as dirty conditions as the red variety. Nevertheless, lump them all into the same category, "tubifex-like worms." Walk into just about any fish store (USA) and ask for live blood worms. They'll give you tubifex. Walk into just about any fish store (USA) and ask for live black worms. They'll give you tubifex! On the other hand, if you ask for frozen bloodworms, you will usually get the correct item, the midge-fly larvae. Recently, the "Kordon" brand has been selling little packets of live midge-fly larvae in breathable bags. These are outrageously expensive, but at least you get the right kind of "Blood worm."

Bottom line: Stay away from tubifex, or any other name that it goes by. Midge-fly larvae are probably going to be OK.

Now that I've talked you out of tubifex, let me back track a bit. I believe the hobby needs some research into the "clean" culture of tubifex. Tubifex is undoubtedly nutritious. The growth rate reported (in all cases that I've read or heard about) is very good. So why not culture tubifex in some type of medium that they can survive in but not live in this massive bacterial colony? When I picked up my pair of Cobalts, the previous owner had fed them tubifex. The pair had been "spoiled," so I had no choice but to continue feeding them the same thing until they were "weaned." During this period, I had heard that a german article reported using small amounts of milk to get the tubifex worms to "barf up" the sludge from their digestive tract. I tried it. I'm not sure if they barfed up anything or not. However, I did find that the worms survived much longer in a container with a small amount of added milk than they did in a container of just plain water. (Note that in both cultures I had to do daily water changes to keep the water from spoiling and killing off the culture.) The amount of milk I added was just enough to make it hazy and hard to see though. You could still see the clumps of worms.

This is an area that requires some research. There has to be a way to culture clean tubifex/black worms. Hopefully I'll get someone out there thinking. Hey, who knows? If you come up with a way to culture clean tubifex economically, you could become rich and famous!