get prime meat fish instantly

I was looking for a mosasaur with my ichyo in the deep ocean and I found this big friend, when I got closer, there were some words under the health bar, scape meat or something, and when i go back home to get some meat then back to this big friend, i get off the ichyo then walk up to him and BOOM, i get 20-30 Prime Meat Fish INSTANTLY, This really happened, but I still have to investigate this further whether this is just a coincidence or is it true that this big friend gave me Prime Meat Fish