I have a 2 ft planted tank which I keep both tiger and CRS shrimps. My 1st batch of tiger shrimplet (8 of them is already more than 1cm in length) but 2 batches of CRS shrimplet did not make it. (1st batch saw 7 of them, 2nd batch saw 2, but they all disappear after 2 days and never appear again.) It is 2 months ago since I saw the CRS shrimplets (approx 0.2cm when first appear). What is the difference in requirements between tiger and CRS shrimplets? Please advise.