Ahimsa or Non-Violence not only against humans but also all living creatures is one of the main preaching of the Jain Religion. The Mantra described in this post is one of those specific Occult Spells, which were composed to save and protect living creatures from harm.
To free a Fish trapped in a Fishing Net- The Mantra given in this post is a Jain Mantra, which has to be repeated as many times as possible, preferably by lighting an incense stick and sitting down in front of it. The more you chant the Mantra, the quicker is said to be its effect in freeing the Fish from the Net.
To prevent Fish from being trapped in a Fishing Net- The practitioner has to take some small gravel in his right hand and chant the Mantra and then blow his breath on the gravel. This has to be done 21 times in all to infuse the gravel with the power and potency of the Mantra. Then the Mantra infused gravel has to be thrown on the target Fishing Net to prevent it from trapping even a single Fish.
ॐ णमो अरहंताणं ॐ णमो लोए सव्वसाहूणं हुलु हुलु कुलु कुलु चुलु चुलु मुलु मुलु स्वाहा ||
Om Namo Arihantanam Om Namo Loye Savvasaahoonam Hulu Hulu Kulu Kulu Chulu Chulu Mulu Mulu Swaha ||