I had been using shallow tubs to purge out my crayfish but had been losing a few to die-off in the process. My brother had an old turtle aquarium that he gave me to use as a holding tank and it works perfectly! I placed some crushed limestone in 1/2 of it so they could get out of the water if the pump failed and left the other end bare. Made sure it was fully enclosed as they will climb right up the wire and would be sitting on top of the pump assembly. They like to crowd around under the waterfall. I clean the filter and change the water by dropping a sump pump in the tank to drain it off, them pour 10 gallons of fresh water back in. 2 weekends ago I had 18 that I didn't boil up so I left them in there the entire week and did not lose any. Saturday morning I dumped another 60 in there and Sunday morning I dumped another 70 for a total of 150 which you see in the pics. I did not have a single one die and it works like a champ! We boiled them all up on Sunday and I froze a few bags of meat for future dishes. I spoke with the DNR field office to make sure I was OK on the possession regulations and he said absolutely...no limit on number or length of time possessed, Just don't use as bait!!!