Sorry, didn't want to hijack the thread :)

We were able to show that the gills of zebrafish grow and get more 'sparse' with endurance training. This means - to our understanding - that the water can more easily penetrate the gills and is transported through the gills more efficient, i.e. the oxygen is extracted from the water more efficiently.

Here's a little bit of the backstory on my 'work' blog: https://micro.tomo.graphics/manuscripts/2019/08/26/adaptatio... And here's the manuscript on bioRxiv: https://doi.org/10.1101/744300

Just yesterday we submitted the 'minor revisions' for our submission of the manuscript to PLOS One :)