The mystery of Les Rouges Truites

The High-Jura is a land of many legends that likes to keep its secrets. Rumour has resulted in four different version relating the origin of the name Lac des Rouges Truites:

Poetic: every evening, when the sun sets, trout take on a crimson hue due to the rays’ reflection on the lake.
Practical: the trout are salmon trout.
Physical: the water is said to contain iron oxide.
Military: the lake is said to have been the site of a bloody battle.

Every day, night falls over the lake, taking with it the mystery of its name. Schubert anyone?