This is an Imam zamin a tradition where coins are wrapped in a cloth and tied around the right upperarm for good luck and safety during weddings, travel, sickness and and new venture.
This is for a bride. In fact mongst Shia Muslims the engagement ceremony is called Imam zamin ki rasm or ceremony.
The fish emblem symbolises prosperity and fertility in the Persian ate culture
It is connected to Imam Ali al-Ridha (Imam Reza) the 8th Shia Imam.
One historical explanation given for this is that during the rule of Mamun al Rashid any pilgrim wishing to visit the shrines of Karbala needed a personal guarantee from Imam Raza.
The Imam gave this guarantee to everyone, establishing his name as Imam Zamin, the Imam of guaranteeing.
Mamun also ordered the state mint to engrave coins with Imam Raza’s name and these were kept on person’s body as a powerful symbol against any sort of calamities. So the Imam became a symbol of guaranteeing safe journey.
Even today we don’t start on a journey or important task without the Imam zamin.
Even from far away I will message my children and loved ones “Imam zamin ki zamanat mein diya” and their answer is “Qubool Kiya”
Once you reach safely you give that coin away as charity in the name of the Imam.
It’s tied on the arm of a sick person for successful recovery.