I just purchased a 37 gallon tank that I will be setting up as freshwater. I need to cycle the tank. I currently have a 40 gallon tank with multiple Comet Goldfish that I have had for a while (some of them years). Can I safely use a couple of the Comet Goldfish to cycle the tank? They are very hardy.
Also would like to add live plants. At what point do I do that, and what do I need in the tank to make them grow appropriately?
Any feedback will be much appreciated!!

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40 Gallon Breeder Tank with 10 Comet Goldfish between 2 and 10 inches long
Just purchased a 37 Gallon Tank and will begin to cycle
What to do, what to do?

You can put one or two of the comets in the tank to cycle, but if you already have an existing cycled tank, why not just put in some of the filter media into the new tank to cycle it quicker? I know many people would say don't cycle a tank with goldfish, but I've done that and my fish are happy and very healthy.

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Never under estimate the power of an empty fish tank

There are some real easy steps to "fishless" cycling, just google that.
And yes you can use the goldfish, and the plants can be added any time. They will help with the nitrates and nitrates.
But definitely use some gravel and filter media from established tank... You'll see in any of the articles that have been previously written.
"Buddha in your tank"

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"Buddha in your tank"

It'll do just as much to add the gravel from the other tank as it would adding fish. Probably help things go faster really. Then you dont have to risk the fish.

Thanks, I set up the current tank on the fly. It was my mom's and when she passed, they were thrown in the new one. Looking at some of the posts here, I'm surprised they survived. I'm definitely going to take some gravel from the old one.

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40 Gallon Breeder Tank with 10 Comet Goldfish between 2 and 10 inches long
Just purchased a 37 Gallon Tank and will begin to cycle
What to do, what to do?