They were then gathered in baskets or speared as they came to the surface. My experience has been with ground up black walnut hull and the berries of polk sallet, though not extensive. I have a friend who uses polk sallet berries extensively by mixing them in the water upstream of a slow moving stream. As it washes downstream there are fish that surface and float on top as if dead. Fish that has been poisoned is safe to eat, as I said earlier it only knocks them out.
Fish poisons work best in a still area of a stream where fish are.
You can also dam up an area. I e-mailed Christopher Nyerges at the School of Self Reliance in the City of Angels and asked him to help us out on the scientific names of the fish poisons I gave out the other day. He not only supplied me with some of the names but gave me some other info I thought I'd pass on. I would be happy to provide you with an article about poisons and how to use them. In Calif. anyway, you're probably referring to Death Camas, Zygadenus sps.