I have been raising european crawlers for I guess about 6 mos. and have them in two heavy duty plastic tubs from home depot. 20"x30"x14" deep. they have done well, and have made plenty of babies, zillions. I need to start one or two more bins, as shellcracker fishing uses up alot of them. I will have to say that the european crawlers are alot tougher or durable than the regular redworms, they don't die under water real fast like redworms either, and the skin is tougher. Illinoisgiller, got me going with a generous couple of seed batches. but they say redworms multiply the fastest of the species. I have had problems with mites in the beds tho, and they are impossible to get rid of, but they don't hurt the worms.