Its been a bad year for clams in my tank. I've lost 4 now out of the 7 that I started the year with. The large maxima and crocea I had for about 5 years each while the squamosa and little maxima I only had for a year or two. I believe that the squamosa may have carried a disease or something that infected the others as it was the most recent addition. From day one the squamosa would exhibit classic signs of pinch mantle. In total I think I gave it 4 fresh water dips which would work for a little while and then the symptoms would return. I also routinely inspected all of them for parasitic snails but never found any.
What really confuses me though is how all of them died. The large maxima looked pinched on a Monday in April and was dead on the Friday. The Squamosa looked pinched for about 5 months starting in the Spring and finally died in October. The following day the crocea which looked perfectly normal the night before as it had for years was dead in the morning. Two weeks later the small maxima died basically the same way the big one had.
The three clams I have left are a 5 year old Crocea, 4 year old Derasa and 2 year old Maxima.
On the plus side the tank continues to look great and everything else is growing almost out of control.
