Observation of a Living Fish - Teacher's Guide

Original Document - Observation of a Living Fish

I usually get a couple dozen fish at the beginning of the year and keep in a large tank, these fish are used for this lab and for the fish respiration lab. Goldfish are cheap but they can be difficult to care for in the long term, make sure you have a filter on your aquarium to remove ammonia - this is the most common cause for goldfish death. At the end of the year, I give the fish away to students who want them.

1.  A goldfish belongs to the Kingdom ___Animalia______,
the Phylum ___Chordata_____________
the Subphylum __Vertebrata____________
and the Class ___Osteichthyes_____________

2.  The goldfish is considered to be a ___RAY____-finned fish.

3. List three other fish that would be in the same class as a Goldfish.

carp, bass, catfish, salmon, guppy, trout, ..etc

4. Goldfish are bony fish, but they are related also to a group of fish who have skeletons made of cartilage. What class of fish does this refer to? __Chondrichthyes, or cartilage fish_

Observation of the Fish

1. Observe the movements of the fish for five minutes.  Record the fishes activities in the space below.  Be specific!

fish will tend to hover in the center of the beaker or circle around the outside

2.  Life the beaker and look at the fish's belly.  Compare the coloration of the ventral (belly) side to the dorsal (top) side.    What is countershading and how does it benefit the fish? The top is darker than the bottom, countershading acts as camouflage, the light bottom of the fish blends with the light coming down from above

3.  Observe the fish as it opens and closes its mouth.   Now look at the operculum.   When the mouth is open, is the operculum open or closed? the gills and mouth open at the same time  

4.  The opening and the closing of the mouth tells you how many "breaths" a fish takes.  Count how many breaths your fish takes in one minute.   Compare this number to to five other fish in the room and record the data below.

Your Fish ______       Fish2  ______       Fish3  _______       Fish4 ______       Fish5 _____ answers vary, 30-60 is common

5.  What is the average breathing rate of the goldfish?  (Add all five numbers and divide by 5)   Average:   ________

6.  Examine the eye of the fish.   Is the eye protected by an eyelid?  __no___   (Hint: does your fish blink?)

7.  Determine if the fish can see your hand by putting it close (but not touching) the glass.   How does your goldfish respond? usually there is a response, but goldfish can become desensitized to the stimulus

8.  Now tap the glass gently and record how the goldfish responds. this usually causes a pretty intense reaction, they will swim around quickly and spastically; this is why its bad for fish to tap the glass of their aquariums

9.  What system is responsible for sensing  vibrations in the water?   lateral line_ system

10.  Examine other goldfish near your table.  Do they all look the same?   What are some of the color variations among the goldfish in the room? gold, black, white, and silver are common colors.

11.  Examine the fins.   As the fish swims, which fins seem to be moving the most? pectoral and pelvic fins move for hovering, caudal fin moves, but its not always obvious

12.  Which fins don't seem to move at all? dorsal, anal

13.  Look closely  at the dorsal fin of the goldfish.  Sketch the fin in detail below.    Why is a goldfish called a ray-finned fish? there are tiny spikes are rays that go through the dorsal fin, these rays can cause injury if you grab a fish the wrong way

14.  Fill out the chart below.

Name of Fin How many present? Function
pelvic 2 steering
pectoral 2 steering
dorsal 1 balance
anal 1 balance
caudal 1 forward motion, propulsion

14.   An analogous structure is a part of the body that is similar to a part of the body in a different organism.    What would be the analogous structure of these fins on a human?

Pelvic fin  _legs, pelvis___           Pectoral fin     ___arms, shoulders________

15. Sketch your fish in the space below.  Label each fin.

fins