Electric Blue Oscar Fish

My future creature is the electric blue oscar fish which lives in the Amazon River. The Amazon River is in a drought at this very moment due to climate change. The Amazon River is turning into a pond very slowly because it is the largest river in the world! My animal will grow legs so it can walk or run from predators, and its color will change into a dark green or brown. The electric blue oscar fish will develop lungs instead of gills,but there is a possible chance that the oscar fish will keep ixts gills if it needs to swim from predators, it can breathe underwater.