Salmon skin story: It's a famous legend in Japan, and there are two basic variation. One version says a lord wanted the salmon to be super thick (as what happened in this chapter), another version says the lord wants the salmon skin to be really big, as in like a carpet.
Typically it'd say that lord Maeda Toshiie of Kaga offered a castle in exchange of salmon skin the size of a tatami mat, and lord Tokugawa Mitsukuni of Mito offered a large territory in exchange of a salmon skin one inch thick. The story can kind of get mixed around about which lord wanted which, sometimes the thickness or the width vary, and the reward they were offering up also can vary.