A fish sticker on the back of a car usually represents the “Ichthys” symbol, which is a simple outline of a fish. It’s most often used by Christians to signify their faith. The symbol dates back to early Christianity, where it was a secret sign among believers.
Sometimes, people also customize it with words like “Jesus” or “Darwin” inside the fish, which can indicate either religious faith or a scientific/atheist sense of humor, depending on the design.
So, in short: it’s either a faith statement or a playful twist on the traditional symbol.
If you want, I can explain all the common variations and what they mean, since some are surprisingly creative! Do you want me to do that?