I ordered 18 Cochu's Blue tetra online. Paid for overnight shipping and I delayed shipment for a week due to the holiday. In 12 hours I've lost 9 of the 20 sent. 1 arrived DOA. My acclimation procedure: Pop and plop: because I have a ph of 8.4, using neutral bottled water, I remove fish from shipping bags asap. They received a 30 minute methylene blue bath to help recover from shipping. Bag water tested .5 ammonia. Then they are moved to a heated acclimation tub, which started with approximately 4 gallons of the spring water, where I add 4 cups of tank water every 15 minutes. Every hour I check the ph. Also monitor the temp, which was stable at 76F. After about 2.5 hours, the ph matched, so they were transferred to the main tank. (Cycled to 6ppm fishless). One died rather quickly, another I noticed had a cloudy eye, was removed to qt where it deteriorated quickly and was eventually euthanized. Overnight 6 more have died, 2-3 more still not doing well. Also received a bn pleco who is doing well. Tank parameters are 0,0,20 after removing dead fish. Is this a usual occurrence? Did I do anything wrong? I have received shipped fish before, with no casualties, but those were all from other members here. I've used the same procedure with all shipments. What would you do at this point?