While you may not catch a fish large enough to inspire a tale, there are decent opportunities for fishing around Huaraz [1]. Stocked lakes, such as Lago Querococha in the Cordillera Blanca [2], are the best option. According to the regulations of Parque Nacional Huascarán, it is illegal to keep fish below 25 centimeters (about 10 inches).
In 2007, there was no rental fishing equipment in Huaraz [1], but Michel Burger of Pérou Voyages (Julián Morales 823, tel. 043/42-6249, www.perouvoyages.com [3]) is an authority on local fishing and can fill you in on the most updated information.
Links:
[1] http://www.moon.com/destinations/peru/huaraz-and-the-cordillera-blanca/huaraz
[2] http://www.moon.com/destinations/peru/huaraz-and-the-cordillera-blanca/trekking-the-andes/cordillera-blanca
[3] http://www.perouvoyages.com