Solid soap isn't any better. All of those work by making fats water-soluble. This destroys mucous membranes and skin slime layer of fish and other animals and breaks down lipid barriers of algae and bacteria.
The real takeaway is that concentration matters a lot: one person washing up for the morning won't kill a pond, but a hundred people or prolonged exposition will.
The real takeaway is that concentration matters a lot: one person washing up for the morning won't kill a pond, but a hundred people or prolonged exposition will.