Fish Facts and ID (GMHDRNC)


Learn to identify the difference in similar fish species and, along the way, learn some facts about Arkansas’ incredible fishes, such as the alligator gar, the paddlefish or the sturgeon.

Grade Level:

K - 12

Recommended Setting:

Indoor or outdoor classroom

Outdoor Activity:



Governor Mike Huckabee Delta Rivers Nature Center, Pine Bluff


Education Program Coordinator, 870-534-0011


45 minutes - 1 hour

Suggested Number of Participants:

10 - 30

Special Conditions:

Can be used as segue to fish collections program


  • Learn the major features of fish anatomy and specific fins.
  • Learn to identify fish species with the dichotomous key.

Key Terms*:

Anal fin

Caudal fin




Lateral line

Pectoral fin

Pelvic fin

Soft dorsal fin

Spiny dorsal fin

Swim bladder

*See glossary for definations


Fish poster with features labeled

Fish specimens and/or pictures

“Fishes of Arkansas”


Arkansas’s ichthyofauna includes more than 200 species. Fish are egg-laying, usually scaled creatures that use gills to breathe underwater. All fish are poikilothermic or cold-blooded, meaning their body temperature depends on the environment.


  1. Explain how unique waterways allow a diversity of fish in Arkansas.
  2. Discuss the basic biology of fish. Draw or distribute a picture of a fish and describe the functions of internal and external features.
    • Internally, fish have several unique organs. Gills are behind the cheek on the head of a fish and filter the oxygen from the water so it can breathe. The swim bladder is an airtight sac within the body cavity that can keep fish suspended at a certain depth. The sac’s air is adjusted depending on the depth at which the fish needs to be safe or to feed.
    • The lateral line and the many fins that steer the fish are the major points of the external anatomy. The lateral line is a row of scales with sensory tubes that detect vibrations in the water, helping the fish to locate food, other fish, or potential danger. Six important fins are the spiny and soft dorsal fins, the caudal and pectoral fins and the pelvic and anal fins. The spiny and soft dorsal fins are along the top ridge of the fish and, while both maintain balance and steer in tight spaces, the spiny dorsal fin mostly defends against predators. The caudal or tail fin generates forward movement, and the pectoral fins (behind the gill on either side) help the fish move up and down or remain stationary. The pelvic fins are on each side of the belly in most fish and are used to position or balance. The anal fin sits behind the vent and maintains balance.
    • Other features are the mucous covering the scales and the specialized mouths of various species.
  3. Using the dichotomous key in “Fishes of Arkansas,” have participants identify fishes from samples and/or pictures, and explain the importance of knowing fish species in relation to the Arkansas Game and Fish Commission regulations.
  4. Point out information on alligator gar, sturgeon and paddle fish.  Have additional pictures and information on display to share with students.  Students typically enjoy a brief study of these because of their immense size and unusual appearance.
  5. Answer any questions.


  • What are some key features of fish?
  • Why is it important to know how to identify fish species?
  • What is the difference between fish gills and our lungs?


Anal fin – a single fin on the midline of the lower or ventral surface of a fish, just before the tail and usually just behind the anus and urogenital openings

Caudal fin – tail of fishes and some other aquatic vertebrates, used for forward motion

Fish – any of three classes (jawless, cartilaginous and bony) of cold-blooded vertebrate animals living in water and having fins, permanent gills for breathing, and, usually, scales

Gills – membranes fish use to absorb dissolved oxygen from the water during respiration

Ichthyology – branch of zoology dealing with fishes

Lateral line – horizontal lines of sensors along the head and sides of fishes and some amphibians used to locate water current and pressure changes, vibrations, food, other fish and dangers

Pectoral fin – anterior pair of fins attached to the pectoral girdle of fishes, corresponding to the forelimbs of higher vertebrates

Pelvic fin – fin on each side of the belly of most fish, used for positioning and balance

Soft dorsal fin – soft-rayed vertical fin on the top of most fish, used for balance and to move in tight spaces

Spiny dorsal fin – hard-rayed vertical fin on the top of many fish, used for balance, defense and to move in tight spaces

Swim bladder – an air-filled structure in many fishes that maintains buoyancy or, in some species, helps in respiration; also called air bladder