As we know our country is the land of Dharma and our country always practiced and propagated higher ethical values. Leaders in this land always gave the message of peace and harmony. You yourself demonstrated living life on higher principles.

All forms of lives are precious. Our country always gave the message of Ahimsa (non-violence) be it Lord Buddha, Lord Mahavira, or Mahatama Gandhi.
By killing the lives of any kind of species ultimately we are acting violently thus acting sinfully.

Fishes do not harm us in any way. They are part of the ecosystem just like any other species. So why we should not be kind to them and let them live in the ecosystem.
Killing fishes in masses would be a violent act that will affect our consciousness. This aggression in consciousness will increase our violent acts towards other forms of life.

NEWS : 

1. India Today 

 After Green and White, PM Narendra Modi calls for Blue

2. Times of India 

 Prime Minister Narendra Modi calls for Blue Revolution to promote fisheries. He says we have to tap the potential by helping Indian fishermen.