Today, it can be seen as a decal or emblem on the rear of automobiles or as pendants or necklaces as a sign that the owner is a Christian.
Versions of this include an Ichthys with "Jesus" or "ΙΧΘΥΣ" in the centre, or simply the Ichthys outline by itself.
If you have any unread mail, Plenty Of Fish will display the number of unread messages.
So in the example below, the user has 17 unread messages in their inbox.
There are several other hypotheses as to why the fish was chosen.