I’m very sorry to hear about the problem you had with your frozen Mysis. I would not trust frozen Mysis that had thawed during transit, and I feel you should discard any Mysis that was not frozen when it reached you. It is true that tainted Mysis will often float due to the gasses of decomposition once it begins to decay, but thawed Mysis can also be contaminated with bacteria on its surface and sink as usual. It is standard operating procedure to ship frozen Mysis on dry ice so that it does not thaw out en route and it is unfortunate that you might have received a bad batch of Mysis.
The Mysis that was still frozen solid should be safe and clean, but I would be suspicious of any Mysis that was not fully frozen when it arrived, and I would definitely ditch the Mysis that had obviously thawed. You should be entitled to a refund, or a new shipment of Mysis, to replace the dubious Mysis that could possibly have begun to spoil before it reached you.
If your seahorses or other fish have eaten any Mysis that was spoiled or contaminated, it would have a similar effect on them to food poisoning in humans. If so, a mild case would simply put them off their feed temporarily and result in a loss of appetite, just as you might lose your appetite after eating a bit of bad potato salad during a summertime picnic. Most of the time the seahorses will recover without any long-lasting ill effects, just as you or I would after scarfing down some tainted potato salad.
As a precaution, I would fast your seahorses and other fish tomorrow so that they can purge themselves of any suspicious Mysis. Get rid of the dubious Mysis that may have thawed en route and use the well-frozen Mysis that you know is safe to feed them the following day. If they feed normally at that time, you can feel confident that all is well and they are going to be none the worse for wear.
Best wishes with all your fishes, Gidget!
Post edited by: Pete Giwojna, at: 2009/04/30 03:05
Post edited by: Pete Giwojna, at: 2009/04/30 03:48