Me and my wife narrow down everything we had done with chubs. the only thing we can come up with is a a gastrointestinal blockage. we fed him mealworms two times a week which we didn't feel was a lot since he was eating every day. We found out later that mealworms can have shells that can cause blockage. That's literally the only thing we can link it to. We plan on getting another frog at the next reptile show and are leaning towards the South African bullfrog again. We have had time to set up an amazing aquarium for it. It's a 55 gallon tank with a full cabinet up underneath. I am a Glazier that works with glass so I am going to divide half of that tank into a gradual walkout aquatic area. And have the other area with the coconut husk substrate. It's going to look really nice. It's going to be a bit of an overkill for a pixie frog for sure.