well even in my other tank its like they will live for a week or two and the start dieing. last batch was good for like 3 weeks and one night i wake up to dead and the other 4 or so died that day. not sure but i have spent over $100 in shrimps and now i give up. was fun but i just think they aren't for me.
if i had to put money on it tho id say it was molting issues.
also each batch i got were from different places/people.