Unicycle Unicyclist Ichthys Sign of the Fish Christian Fish Symbol Monowheel Unicycling Ichthys or Ichthus / ΙΧΘΥΣ now known colloquially as the "sign of the fish" or the "Jesus fish. The ichthys is seen in first century catacombs in Rome. According to tradition, ancient Christians, during their persecution by the Roman State in the first few centuries after Christ, used the fish symbol to mark meeting places and tombs, or to distinguish friends from foes … when a Christian met a stranger in the road, the Christian sometimes drew one arc of the simple fish outline in the dirt. If the stranger drew the other arc, both believers knew they were in good company.