I just received a shipment of cured live rock on Thursday evening. The rock travelled to me by bus and was in transit for nearly 36 hours. Although the rock was well-established, there was some die-off during shipment. When it got to me, I cleaned it as best I could and put it in the empty aquarium (sg 1.026, temp 79-80F). Almost immediately 2 tiger tail sea cucumbers emerged. They looked healthy. Because of the die-off on the rocks, & the resulting curing/cycling, I assumed they would not survive because I understand they do not tolerate high nitrate levels. I was right. They are both dead today. I was able to retrieve one from the tank (while it was dying.. it's organs were being ejected out it's rear) but the other is deep within a rock and I cannot reach it. I am wondering about the holothurin which they most likely released into my tank... I understand this is toxic to fish, but what about other marine life like invertebrates? Will it affect the life on my rock? How long will the toxin remain in the water? Do I need to do a 100% water change before adding fish or will my protein skimmer get rid of the poison. If so how long will it take? Does anyone know? I can't seem to find any information on the internet. Thanks.