A little background, I recieved an order of 26 crested chicks (mostly Polish). All the chicks looked great when they arrived. I lost one the next day, but attributed that to shipping stress. I opted to treat them all for coccidiosis (Corrid in water 10ml/gal for 5 days). I lost three more in the next five days, but then everyone else seemed fine. I thought I had solved the issue. At three weeks, I lost a couple more, and this trend has continued sporadically. I treated once more for coccidiosis, they remain on medicated chick starter and I keep vitamins and electrolytes in their water. Most pass without any symptoms. I contacted the hatchery who was not overly helpful. At the time, I actually caught one passing. In her last minutes, she was very weak, and star gazing. I sent the hatchery the video and they said, looks like a vitamin deficiency. I get that, but I don't know what is causing the deficiency. That was nearly three weeks ago. The remaining six chicks from the shipment have seemed fine since then, but just this morning, the largest and healthiest of the group is lethargic. She's hanging her head and is overall weak. I gave her additional vitamins, but it really doesn't look good. Whatever is happening seems to be isolated to the crested chicks. I have several other chicks that all seem to be just fine. The birds that it impacts do seem to go anemic almost overnight, they look a little off, and pass. I think the hatchery is correct in that it's a vitamin deficiency, but I can't seem to isolate the underlying cause of the deficiency. At this point, I am seriously considering culling the remaining birds out of fear that they may have something that can be passed on. I've contacted the vet about doing a necropsy on the bird who is currently sick, but I really would prefer that she doesn't end up in a condition that would lend itself to a necropsy. As non emotional as my text may seem, this group is one of my favorites. The sick one in particular is a character. The thought of culling them is a tough one, but I'm genuinely concerned that there may be something more going on with this group.