i used to feed the oscar in my avatar Canadian Night Crawlers from the fridge in the sporting goods department at my local wal mart. no problems. he loved 'em
I feed red wigglers from my home composting bin to cichlids of all sizes. These guys are really easy to culture and will eat your fruit / veggie kitchen scraps...
I've also fed earthworms that I've bought and collected from the yard. Never had a problem with either...
I've yet to hear of a story of someone's fish dieing after eating an earthworm collected in a yard. Seems like self perpetuating Internet lore to me.
Nightcrawlers are just bigger! Worms are high in protein!good for conditioning fish! Just make sure no fertilizers or insecticides are being used if you catch them yourself. I feed worms almost daily! I feed a few different foods everyday. Some pellets a worm or two, maybe some krill or bloodworms ect. Just feed least liked food 1st with their favorite food last. I stole that trick from my parrots!lol. IMO worms are highly overlooked as a great food source that they are! I've fed worms for over 20years n NEVER had a problem with them! Although word of CAUTION! While a worm can n will live a few days in your tank if the die in there they MUST be removed ASAP!!! But if your observant when you feed n don't overfeed you'll be fine!
I feed nightcrawlers from my LFS. They only cost $2.50 a dozen. The advantages of getting them from a store is that they always have a year-round supply. That allows me to buy them in the winter. Plus, I know that they're clean.
You mean you hope their clean! You have no idea where they were raised or what they've been fed. Less your Lfs raises them his self. Worms are usually raised for fishing not feeding tropical fish. But like I said earlier I've never had a problem with feeding them. I assume their clean too!