Handbook of Nature-Study · Lesson XXXVI · Topic 3: Fish study
36. A study of the fish (the goldfish)
Goal: Your child can name a fish's fins and tell what each does, and explain how a fish breathes, sees and is shaped for life in water.
You'll need
- A goldfish in a bowl or tank (your own, a friend's, a classroom's or a pet store's)
- A labeled picture of a fish's fins (Comstock prints one on page 150)
- Pencil and nature notebook
What's in the book
An introduction to fish study (keep brook fish only a few days, and put them back), then the leading thought, the method (a goldfish, with the labeled fish diagram on the blackboard) and eighteen questions about shape, every fin and how it moves, scales, the lateral line, eyes, nostrils, mouth and breathing, colors, and where goldfish come from. A poem by Lowell, "The Oracle of the Goldfishes", follows.
The lesson, step by step
When and where
Any season, indoors. A pet goldfish is perfect. Pet stores and many libraries, doctors' offices and restaurants have tanks too. Comstock says a shiner or minnow would do as well.
Keep the big idea in mind
Read this to yourself:
A fish lives in the water where it must breathe, move and find its food. The water world is quite different from the air world and the fish have developed forms, senses and habits which fit them for life in the water.
Shape
Sit close to the tank and watch quietly.
What is the shape of a fish when seen from above? Where is the widest part? What is its shape seen from the side? Think if you can in how many ways the shape of the fish is adapted for moving swiftly through the water.
Fins
Open the book to the labeled fish picture.
How many fins has the fish? Make a sketch of the goldfish with all its fins and name them from the diagram on the blackboard.
Four of these fins are in pairs; where are they situated? What are they called? Which pair corresponds to our arms? Which to our legs?
With what fin does the fish push itself through the water?
Watch them move
Watch the goldfish swim and describe the action of all the fins while it is in motion. In what position are the fins when the fish is at rest?
Describe the pectoral fins. How are they used? Are they kept constantly moving?
Eyes and breathing
Note carefully the eyes of the fish.
Does the fish wink? Has it any eyelids?
Is the mouth kept always in motion? Do you think the fish is swallowing water all the time? Do you know why it does this?
Does the gill cover move with the movement of the mouth? How does a fish breathe?
Gold in the wild
What would happen to our beautiful goldfish if they were put in a brook with other fish? Why could they not hide?
Comstock's story says goldfish came from China, where their wild ancestors were olive-green, and that escaped goldfish turn back to dull colors. Never let a pet goldfish go in a pond or stream: it can harm the fish and plants that live there.
Nature notebook
Draw the goldfish from the side, all its fins showing, and label them: dorsal, tail, anal, the pair of pectorals and the pair of ventrals. Ask your child to tell you the leading thought in their own words, then share Comstock's.
Afterwards
Watch the fish for two minutes at a time on other days. Count how often the gill covers open in a minute.
Tip
Comstock suggests linking the goldfish to a geography lesson on China. Find China on a globe or free online map.