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Caffeine and Goldfish

Postby monkey133 » Wed Sep 16, 2020 1:42 pm

Hi, I'm doing a science project to see how caffeine effects fish heart rate. I know I can find the heart rate indirectly by using a dissolved oxygen kit to find the respiration rate but how do I translate the respiration rate into the heart rate? Also any others tips would help.

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Re: Caffeine and Goldfish

Postby jcanno17 » Fri Sep 18, 2020 2:27 pm

Hi monkey133,

Sounds like a really interesting idea! First, I think it may be hard to translate dissolved oxygen to heart rate so it might just be a better idea to stick with respiration in general. In terms of dissolved oxygen, this may not be the best way to assess respiration by the fish. In water, the fish will be using its gills to remove oxygen from the water in order to breathe. However, I imagine the fish will not effect the amount of dissolved oxygen very much. Also, dissolved oxygen is dependent on several other things such as temperature, movement of the fish, etc.

The way I would suggest tracking respiration is by keeping a timer and counting the number of times the fish 'breathes' during one minute. Breathing can be counted by the number of times the fish opens its mouth or by the number of times the flaps on the side of the fish, called operculum, open and close. This would give you an indication of the respiration rate as 'breathes per minute.'

Here is a website that describes the procedure for a similar project to what you are thinking of doing: ... ger%20fish.

You will also want to include a control fish that you do not give caffeine and count its breathes per minute. Also, it may be a good idea to count breathes per minute immediately prior to adding the caffeine so you can see how much its breathing changes.

It sounds like you have a really interesting idea here and please let us know if you any additional questions!

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Re: Caffeine and Goldfish

Postby julieslake » Sat Sep 19, 2020 11:06 am

Hi monkey133,

Adding to what jcanno17 recommended, I would also suggest measuring the respiration rate (number of breaths or gill movements per minute) at different time points after adding the caffeine. For example, you could measure respiration rate right before, right after, 5 minutes after and 10 minutes after adding the caffeine. You could also consider testing different doses of caffeine to see how this affects the respiration rate of the fish. This would allow you to graph caffeine dose (in mg) versus respiration rate.

Let me know if you have any questions!

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