Agreed. I’ve seen them swimming free in rivers, even those 3 meter zoo tanks are nothing compared to hundreds of miles of rivers. If we were to consider them swimming free thriving then we shouldn’t keep them in aquariums at all. It’s all a matter of perspective and definition.It's really a comment in relation to 20 litres being enough space for 20 tetras, I've seen these in display tanks at zoos (warsaw/berlin) and they will dart the entire length of 3 meter displays in a flash - they're some of the most active fish we could keep, 20L just feels horrifically cruel to me. Perhaps our definition of thriving is a little out of sync.