My only concern is that there are not enough snails in his tank to support him. He was fed black-worms at the pet store which I do trust a lot. He said that they normally go down and to the worms and ate them like pasta. As for the Danios he does not seem to be bothering them. I have also heard that the Puffers hunt in packs in the wild. I'm not sure if this is true because I have mostly heard they are solitary. I also tried feeding him crabs but he took no interest.