How different are the respiration in fishes and the respiration in adult amphibians?
In fishes gas exchange is completed by direct contact of water with the branchiae (gills). Gases gain and exit the circulation by the gills.
In adult amphibians gas exchange is done by the moist and permeable skin (cutaneous respiration) and also by the lungs, a set of tiny airway terminations associated to a highly vascularized tissue specialized in gas exchange.
The axolotl is an exotic amphibian establish in Mexico that lives in water and "breathes" by gills even as an adult.
Frog Facts Review - Image Diversity: axolotl amphibian skin