I've been buying blackworms from my LFS for 6 mths now, no ill effects. THE ONLY LFS I go to is 20-25 mins away. Around Christmas, I couldn't make the trip to the LFS for about 3 weeks. I was surprised in that short a time what a difference there was in my discus, in size, growth rate, color and even attitiude (friendliness). I was shocked. I got tired of paying LFS prices, so yesterday I put in a standing order with California black worms for 1/2 lb twice a month. I'm sure I'll up it. Hope this helps.