Some of you all with these feeder troubles might need to up the water change schedule on the feeder tank. I use to treat my feeder tank just like a normal aquarium. But it reality its a aquarium with a bio load that is very high at one moment and low the next. Like when you dump in a new batch and there were very few left in the tank for the last few days the bio-bacteria were dieing off and then you increase the bio load all at once. i had the same trouble for a long time. But I know keep a revolving number of feeders. I have a 55g with a 20g sump filter and keep a 150+ minnows in it at all times. i use about 3-4 dozen a week and i buy 3-4 dozen a week to keep the bio load high. I have had no die offs for a year or so, since I got this method established.