||by KELLY LEVY
Henry Viscardi School
Albertson, NY 11507
and ANDREA WISE
Notes to the Teacher: to top
36-48 hour Zebrafish embryos
Compound or Dissecting Microscope, with 4X and 10X objectives.
medicine dropper or pasteur pipette
stopwatches or watches with a second hand
concave microscope slides or small petri dishes
The Zebrafish website is a complete guide to care and lab use of Zebrafish. Zebrafish (sometimes referred to as "danios") are one of the easiest breeds of fish to maintain. Zebrafish can be purchased from almost any pet store. They are easy to keep if you treat them well. Here are some tips:
Zebrafish need dechlorinated water which can be created by aging the
water for 24 hours before use or you can buying bottled water. If
your area puts chloramine in the water you need to buy bottled water because
aging will not remove this substance. (To find out if your water contains
chloramine you need to call your local water authority.) To keep
producing embryos for future experiments you will need at least 2 - 10
gallon tanks. A ten gallon tank can hold anywhere from 25 to 50 fish.
One tank for breeding adults, and one for embryos/fry. Zebrafish
will lay eggs but they will cannibalize them. A dish of marbles should
be placed on the floor of the tank. Fertilized eggs that fall between
these marbles will not be eaten. The eggs can be siphoned or
pipetted from the marbles and put into petri dishes of embryo media.
(This can be obtained from a pet store or made, see recipe in teacher information.
For further info, see fish net website
To lay eggs the fish need to be on a 14 hour light cycle (14 hrs of light/ 10 hours of dark). They will lay eggs in the morning when the light is first presented to them. If you keep them covered you can get them to spawn when you want them to but the photoperiod must remain constant. The eggs have an 85-100% fertilization rate so once you get them your on your way. If you feed the fish 2-3 times a day with fish food obtained from your local pet store you can keep them happy and producing eggs every second or third day. The fry need to eat baby fish food that can be obtained from your local pet store (you are going to get to know the guy at the pet store really well) or you can feed them paramecium until they are 9 days old. At 9 days you can begin to wean them to brine shrimp. They should remain separated from the adults until they are 3 months old. At this point they are ready to begin breeding and will not be eaten by the older fish.
1. To observe the heart rate in developing zebra fish
2. To relate the environmental conditions to the zebra fish development
3. To create a standard curve to predict the temperature an unknown group of zebrafish were
Compound or Dissecting Microscope (or magnifying glass with base)
Small petri dish
Pasteur pipette or medicine dropper
Samples of ZebraFish raised at room temp (17oC to 22oC), 28oC and 35oC and one raised at an unknown temperature.
1. Read the entire lab and all questions you will be responsible for answering before starting
2. Remove a single embryo with a pasteur pipette or medicine dropper from a stock of zebrafish
that have been raised at room temp (17oC to 22oC). Place the embryo in a petri dish with
embryo media from the original stock.
3. Place the dish under the dissecting microscope or magnifying glass.
4. Locate the heart of the embryo which should be slightly below the head.
5. Designate who in the group will be the timer, counter and recorder.
6. Practice counting the heart beat for one minute. You should do this 3 times and alternate the
activities so everyone in the group has had a change to be the timer, counter or recorder.
7. Average the three counts at room temperature and put that in your data table.
8. Return the embryo to the original tank and obtain an embryo raised at 28oC.
9. Have each student again take turns timing, counting and recording the heart rate at 28oC and
place the average in your data table. Return the embryo to the appropriate tank.
10. Repeat this procedure for the embryo at 35oC.
11. Obtain an embryo raised at an unknown temperature and repeat the same procedure rotating
tasks and using the average in your data table.
|Incubation Temperature||First Trial||Second Trial||Third Trial||Average Heart rate|
6. According to the graph, what is the unknown temperature that some
of the embryos were raised at?
7. Predict the heart rate at 30o C.
1. Could you repeat this experiment for chicken embryos and expect to
see the same results?
2. Factories once used water to cool their machinery and dumped the warm water back into the lakes and streams which it came from. This is called thermal pollution. What effect do you think thermal pollution could have on the stream ecosystem?