[ It's a good sign that she acknowledged her mistake rather than trying to defend herself. Setsuna regards that admirable, so he looks on with soft eyes especially after she asks on what to do.

He stays at the side of the river, gesturing his hand so she would leave the water and stand by his side instead. ]

I shall explain why it is dangerous. First of all, the increasing amount of deceased fish may result into biological decay if left in the waters and could lead to lack of breathable air for its inhabitants. Secondly, it is not recommended to slay the fish immediately as the longer the body is exposed to heat and air, the more its quality lowers in turn. To ensure its fresh quality, keep them alive until it is time to cook them.

[ Is he going too fast? He pauses now, first allowing those information to go through her before he would continue anything else. ]