After the live food experiment earlier this year, many students noticed the fish breathing (not an indicator that it ate daphnia!) We know they don’t breathe quite like us, so how do they do it?
Breathing
Check out this video from South Seneca a couple years ago, showing a trout breathing. Make some observations:
How many breaths did it take?
Which part of its body is moving?
What kind of water is the fish sitting in?
Warm, cold, oxygenated?
How It Works
Our trout breathe using a special organ called gills, which helps them remove oxygen from water. Fish take in water through their mouth (something you and your students may have observed already) and it passes through their gills when they exhale. When it does this, the oxygen is diffused into the bloodstream and through the body.
What Effects Breathing?
Just like how the amount of oxygen in the air changes how much we breathe (ex: on top of a mountain vs at the bottom), the amount of oxygen in the water will impact how much our fish breathe. Remember how we talk about our fish liking cold water? That’s because cold water holds more oxygen than warm water! In our aquarium, we also see something called the bubbler, which mimics oxygen entering the water as it tumbles over rocks in nature. Trout like highly oxygenated water. If warm water has less oxygen in it, do you think our trout would breathe more or less in warm water? When we release our trout at the end of the year, do you think their body will be under less stress in May (cooler water) or June (warmer water)?
Test It Yourself
Here is a copy of an experiment you can run with your students about trout respiration!
