I recently got a cleaning crew for my tank and everyone seems to be doing OK except for my cleaner shrimp. oth of them have died in a matter of 4 days. My nitrite and ammonia levels are undectetable. I used the drip method to acclimate them, and my nitrate levels are only 2.5. Tankmates include a lawnmower blenny, a pair of clowns, and a pair of green chromis, and an assortment of crabs, and snails. Any idea what else it could be?