Sorry about blueberry. I didn't have mine long but had fry only a few days old and winter storm knocked out the power for two days. House temp dropped to 43 F. I wrapped tanks with blankets. Smaller fry tank got too cold and lost all but 6 which I transfered to the large tank with fake grassy matt turned upside down at surface. Fish in there were huddled and near motionless mid water. Figured the larger water volume if not eaten would be better than certain death in smaller. All are active again there but like you still mourn for ones lost.