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Fish Anatomy and Fish Dissection Lesson for Middle School Biology


I am a Christian. I was an 8th-grade American History teacher. I am currently a freelance writer, public speaker, & homeschooling mom of 9.

Christian Middle School Biology Lesson: Fish Anatomy and Fish Dissection

Christian Middle School Biology Lesson: Fish Anatomy and Fish Dissection

This is the 19th lesson in a series of 32 hands-on Christian lessons covering middle school biology. This lesson focuses on fish. Review basic fish anatomy, test out mouth brooding using jelly beans, dissect a fish, & more. I used this plan while teaching a 55 minute middle school biology class. Each lesson plan includes homework assignments and a variety of hands-on activities to make each lesson engaging & memorable. Use these fun lessons with your classroom, homeschool, after-school program, or co-op!

These lessons are written for a class that meets once a week. If your class meets 5 days a week, simply do this lesson one day a week and use the homework assignments (at the bottom of the page) for the work for the other days of the week.

Homework Review

1. Pass out tickets for students who did their homework and who did the extra credit. Go over the homework questions from the book. (I give out tickets for students who volunteer to answer the questions.)

Traits of fish

Traits of fish

Traits of fish

(Note: Go through the notes quickly so that you can have half the class to dissect the fish.)

2. Ask students to name the traits of fish: vertebrates (phylum chordata), exothermic (cold-blooded like amphibians and reptiles), aquatic, and with gills, fins, & scales.

3. What's the weirdest-shaped fish you can think of? (Allow students to share.) Fish come in a wide range of body shapes (stingray, seahorse, tuna, lamprey) and sizes: from the smallest vertebrate in the animal kingdom...who can name it? (5/16 inch carp) to the largest fish...which is what? (60 foot whale shark)

4. Why likes to eat fish? My family doesn't love fish, but I feed it to them anyway. Why is fish healthy for you to eat? (provides protein, vitamins, & minerals; fish oils are rich in vitamins & fatty acids)

5. (Optional) Allow students to try a few different types of cooked fish. *Make sure to check for allergies first!*

You will need:

  • a few different types of cooked fish
  • small plates, toothpicks, or forks
Classification of Fish

Classification of Fish

Classification of Fish

6. What do we call scientists who study fish? (ichthyologists) Ichthys and ichthus mean fish in Greek. Whenever you see one of those root words, you'll know it has to do with fish.

7. Ichthyologists scientists divide fish into 2 classes. What are they? (bony = osteichthyes and cartilaginous = chondrichthyes) Are there more bony fish or cartilaginous fish (95% of fish are bony.)

8. Each class is divided further. The bony fish are divided by what? (fins = ray-finned and lobe-finned) The cartilaginous fish have skeletons made out of what? (flexible cartilage). They're divided further by what? (jaws = with or without jaws)

Anatomy of fish

Anatomy of fish

Anatomy of Fish

9. Fish are pretty different from us aren't they? God designed birds' bodies to fly. He designed bodies of fish to do what? (swim) How are they designed to swim? (long body with tapered ends & glands in skin that secrete protective later of slimy mucus to reduce drag)

10. Who can name each of the fins? (pectoral & pelvic = rudder, paddle, or break; dorsal & anal = stabilize fish while swimming, & caudal/tail = propeller)

Looking at fish scales

Looking at fish scales

11. Discuss scales.

  • We're covered in skin. Fish are covered in what? (scales)
  • Are they all the same on fish? (No)
  • Who has pet a shark before? What did it feel like? (Pet 1 direction and it's smooth; pet the other direction, and it will cut up your hand badly.)
  • Look at the scale shapes in your book on p. 269. Fish have what type of scales? (placoid)
  • Most fish have which types of scales (cycloid & ctenoid)
  • Catfish & eels lose their scales as adults.
  • Do most fish grow new scales as they get larger? (No) What happens? (Some have scales that grow larger like the tree rings)
  • (Optional) Look at fish scales using magnifying lenses.

You will need:

  • fish scales (from specimens you'll be dissecting
  • magnifying lenses

12. Let's talk about the internal structure. Why has eaten a fish with the bones in it? There sure are a bunch of bones. Why? (gives added support to attached muscle) What are myomeres? (W-shaped bands, which have a separate nerve controlling each one allowing fish to swim with wavelike motion & great efficiency)

13. Respiratory system: How do fish breath? (gills filters 80% of the oxygen out of water) We'll see the gills when we dissect the fish. They're really neat to see! What hard plate covers the gill anatomy? (operculum) Who can name a fish that can live outside the water? How does it do that? (Look at pp. 273-274 for the answers.)

14. Circulatory system: Does a fish have a 4 chambered heart like us, mammals, and birds? (No, they a 2 chambered heart with 1 atrium & 1 ventricle. The ventricle pumps to gills to blood; when the blood comes back, it goes to the atrium.)

15. Digestive & Excretory system: Why did God make the mouth, throat, esophagus, & stomach in most fish make a straight line? (so it can eat prey whole)

16. Nervous system:

  • Tell me about a fish's brain. (simpler brain than in mammals)
  • What about a fish's eyes? (large optic lobes = good eyesight - most even see color)
  • Can they hear? (their ears are internal = sense sound waves as changes in pressure)
  • What sense do they have that we don't? (lateral line = nerve endings extend over head & sides allowing to sense vibration & pressure changes = judge distance when maneuvering between obstacles & detecting prey
Trying caviar - This is the brand that costs about $8 for a container at Walmart.

Trying caviar - This is the brand that costs about $8 for a container at Walmart.

17. Reproductive system: What name do we use for fish reproducing? (spawning) In most fish, the female lays lots of eggs called what? (roe) The male fertilizes it with a fluid which contains sperm. What's it called? (milt)

18. (Optional) Some people think fish eggs are tasty. What do we call them (caviar) Has anyone tried caviar? Well, now is your chance. If anyone would like to try some, you can get a small spoonful on a cracker. It tastes very fishy. *Ask about fish allergies first.*

You will need:

  • caviar (such as the Romanoff brand sold at most grocery stores and even Walmart for about $8)
  • crackers (such as Ritz)
  • napkins
Mouth brooding with jelly beans

Mouth brooding with jelly beans

19. (Optional) Some fish lay their eggs on the surface of the water. Trout & some other fish build nests.

  • Most fish leave, but not all. The male jawfish is a mouth brooder, holding the eggs in his mouth until they hatch...and sometimes even after that if they sense danger. Let's try that.
  • Pass out 10 jelly beans to each student to hold in their mouths. Don't eat your babies!
  • A female seahorse lays her eggs in a pouch in the male's abdomen.
  • A small fish is a fry.
  • Some fish give birth to live younger, so they're called livebearers.
  • You can now stop pretending to be that jawfish. You can chew up and swallow your baby fish eggs.

You will need:

  • 10 jellybeans per student
Using a balloon and water to demonstrate how fish bladders work

Using a balloon and water to demonstrate how fish bladders work

20. Fish have 2 special organs.

  • Which one lets they stay suspended in any depth of water? (swim bladder) How is it kind of like this balloon?
  • People have used a similar design in submarines.
  • Which fish doesn't have a swim bladder (bottom dwellers like flounder)
  • Some also have electric organs near their tail with specialized muscle or nerve cells with cells called electrocyles that can be used for communication, stun prey, or deter predators. Who can name a fish with electric organs? (electric eel, torpedo, electric catfish)

You will need:

  • balloon
  • bowl of water (optional)
Dissecting fish

Dissecting fish

21. Dissect fish. You can use this fish dissection lesson plan to provide you with procedures and questions if needed. We didn't measure the fish and we didn't fill out paperwork. We just observed it externally and internally and discussed what we saw.

You will need for each group of 3-5 students:

  • a dead fish - I've dissected fish with groups of students at least half a dozen times. We're purchased whole fish at Asian markets and used perch caught from a local pond. This time we used preserved ones. I wouldn't recommend that. They were so tough and smelled horrible. Get fresh fish.
  • disposable gloves (for all the students)
  • dissections tools: either dissection kits or a sharp pairing knife and a hard, disposable plastic plate
  • disinfectant wipes (1 container)
  • Lysol or other air freshener (1 container) (optional)

22. Clean up

What I use to get extra information for my lectures and to study more in depth with my family

A Beka's Science: Order & Design science textbook

A Beka's Science: Order & Design science textbook


Page numbers refer to the pages in A Beka's Science: Order & Design.

  • Friday: Read pp. 185-187. Answer 4 questions of your choice from p. 188 (Section Review 6.3 – NOT Chapter 6 Review) (Skip Check it Out on p. 187.)
  • Monday: Read Wonderful Worms. Highlight or underline 5 bits of information you think are interesting or important.
  • Tuesday: Read Curious Clams. Highlight or underline 5 bits of information you think are interesting or important.
  • Wednesday: Read Stunning Starfish. Highlight or underline 5 bits of information you think are interesting or important.
  • *Extra Credit #1: Bring a live worm to class (in a container with moist [not wet] soil)
  • *Extra Credit #2: Read Evolution’s Biggest Hurdles. a) Underline a main idea of each paragraph. b) Next to the starfish, write a 1-2 sentence summary of the article. c) Put a star next to something in the article that you thought was interesting.

© 2019 Shannon