Traditionally done on the first afternoon of Rosh Hashanah, it is an act that symbolizes throwing away our sins and bad deeds, so we can have a clean, new start for the New Year. He laughed again and pinched my cheeks. I was told that the holy fish would be brought over to the pond just in time for the holiday, and removed a few weeks later, to some fish market in town. I starting researching the history and meaning of Tashlich, which led me into the world of magic, symbolism, Jewish mysticism, and many questions do not have any answers at least, not yet. Tashlich, I've discovered, is indeed a mystery.
Nobody knows for sure when or how or where the custom developed.
It was maybe adopted somewhere along the development of Jewish history, and a few appropriate verses from the Bible were added later. By the time of the Middle Ages, in Europe, a Tashlich prayer was already written in some prayer books. Some interesting legends link this ritual to a fable about water or to another parable involving fish, but it is clear these stories exist to justify an already existing custom. A great deal of what goes on during the High Holidays is about the words we say, we think, we pray and sing. Basically, we are involved in the verbal process of acknowledging all of who and what we are, and how we wish to change our selves for the better.