Originally posted by Bill Cody:
...Presence of numerous small fish is evidence that the kill was due to a DO shortage. Big fish almost always require more DO than the smallest fish, thus when an oxygen crash occures bigger fish die and many smaller fish survive.
This is true in every sense, but there is one "exception", and that is if you are running a surface agitator, such as that mentioned by Ryan Freeze, that you may possibly lose all of the small fish first, because they will not come to the higher oxygen area near the agitator. The smaller fish will languish around the dead and dying peripheral vegetation and perish. I've seen this twice, and once very recently in a post that I will soon be presenting.
