Live Marine Rotifers
The Brachionus plicatilis (L-type) species is euryhaline, capable of thriving in salinities of 5-40 ppt. It is available in quantities from 1 million to 1.5 billion, concentrated and packaged into "breathable" bags.
Customer service is excellent. Packaging is good. Never have an issue when I place an order.
I will admit to not exercising due diligence as a customer - I didn't count how many rotifers I actually got, but it sure did look like a million!
Seriously though, the rotifers arrived in great condition, just in time since I ended up needing some rotifers the next day as it turned out, and the culture got off to a very fast start despite starting to do some harvesting the second day (though it is not ideal to start harvesting so soon, I was able to do some moderate harvests for feeding some new larvae every day starting the day after the rotifers arrived, and then heavier harvests after about three days - they are being fed Rotigro Plus from Reed Mariculture).
The order was shipped promptly the first weekday after I ordered (I ordered late on a Friday), and arrived when expected. They were packed really well and arrived in perfect condition (as is always the case with Reed Mariculture orders).
Reed Mariculture is great! (And Reed Mariculture's TDO food is fabulous too - the best pelleted fish food I've ever used.)