I do have a massive black one but I've never seen him go for one and as he hasn't bothered eating for three days he couldn't have accidentally bitten the last one left in the tank. It always starts the same, with a small slither missing the the tail starts disappearing. My big guy has always ate two worms now he isn't touching food, before he could smell it the minute it went in. The only thing is that they lived fine together for months now they're going one by one. I even have a large fan on the tank to keep water at 65 as it was going up with the weather. They always got fungus in the torn tail so I treated it with tap water baths 15 mins. I've also put Indian almond leaves in the tank for now to help prevent it. I'm stumped and upset I've lost 3 now. Her gills got less and less same as the others then the tails. I'm wondering if it's the supplier I can only get them from one place.