Final answer:
An adaptation in a fish living in a slow-flowing stream is extra gills for oxygen extraction.
Step-by-step explanation:
An adaptation that could be found in a fish that lives in a slow-flowing stream is extra gills, which help in extracting oxygen from the water efficiently. The slow-flowing stream may have lower oxygen levels compared to faster-flowing rivers, so having extra gills allows the fish to obtain enough oxygen to survive.
Learn more about adaptations in fish living in slow-flowing streams