He passed tonight before bedtime. Lessons learned although I'm not sure what to take away from this one. A close physical exam showed that his lower jaw just rotted away. Whatever it was, it didn't respond to metroplex or furan-2. Since I didn't have any kanaplex, maybe that is the answer. So tomorrow I'll do a 50% water change and observe the rest for a week. If all goes well, I'll move them to the DT next week.