A Fish symbolises God's Son, Jesus Christ. The symbol comes from the Greek word for fish is 'ichthys', which the Christians made an acrostic from this word that translates to "Jesus Christ, Son of God, Saviour'. There isn't a specific meaning that the fish has to someone who isn't Christian, many people would associate it with Christianity.

A dove symbolises the universal sign of peace, in the old testament a dove returns to Noahs ark with an olive branch to show that the waters were going down and that God had made peace with the world.
Although Jews never used the dove as a symbol of peace it got that meaning from early Christians.
When shown with a halo the dove is also a symbol of the holy spirit. To someone who doesn’t follow the