I really wouldnt care if it was a safe worm or not, anything with parasites is NOT going in my main tank.
If a worm is living on another creature, thats a parasite. Whether thats harmful to fish, I dont know. Either way I wouldnt want those things in my tank. If they can live in a river or stream than my tank is like a hot tub.
Most wild crays are going to be too aggressive for a 55. Even if there are plenty of hiding spaces. Eventually 1 will be a bully and eliminate his competition.
Plus if you have fish they need to sleep at night and you dont want several crays running around in there pinching them while they sleep because they like to hunt at night. I usually give mine a nice meal befor i shut the lights off. 1 cray is ample in my 80gal because he is super active
*Keep them in quarintine with 1/2dose of salt for a couple weeks. Or until worms are not visable. Thats what I did. They are super healthy and parasite free now.
