As always with anything that changes, double check your water parameters. Usually (but not always) they decline more slowly and will slow their eating until they stop. Being older and placed into a tank may alter this behavior and we see a lot of differences in individuals. This was so immediate that I wonder about the food as we have seen deaths associated with polluted crabs. Many times we just don't have an answer.
We are a participant in the Amazon Services LLC Associates Program, an affiliate program designed to provide a means for us to earn fees by linking to Amazon and affiliated sites.