Where can I buy piranha in UK?

I’ve heard that piranha is delicious (for some) and I’m curious about it. I live in Surrey, UK. I’ve checked various supermarkets (Tesco, Sainsburuy’s, …) and found nothing. Even Amazon says "No results for piranha in Grocery". General online searches seem to be about piranha as a dangerous animal, a pet, etc., but not about piranha as food. Also, buying a pet fish to eat seems rather expensive, I expect because live fish is more expensive to keep and transport to a shop.

So, is it possible to buy piranha as food in UK (preferably Surrey), how and where?