Increasing numbers of papers, blogs and advocacy campaigns correctly observe that freshwater biodiversity (in its hierarchical construct) is declining rapidly. But there are also authors expressing the same views for other ecosystems. The result is this special pleading, separating freshwater biodiversity from the rest of terrestrial biodiversity, produces a distorted picture of the research and actions needed to develop informed policy and decision-making, and thus improved stewardship of freshwaters. A key issue for effective and informed stewardship of freshwater biodiversity is promoting a research focus through the integrated lens of landscape connectivity and ecohydrology. Co-designing such integrated research that recognises the four-dimensional nature of freshwater ecosystems with early input from policymakers, decision-takers and holders of indigenous and local knowledge can result in a reversal of the decline seen in freshwater biodiversity. And in turn, better support for linked “terrestrial” biodiversity.