There is definitely no need to use fish to cycle a new tank! It is an unnecessary and inhumane method, increasingly frowned upon by serious aquarists.
I successfully used household ammonia to cycle a brand-new 5-gallon aquarium. It is easy to do so, and the cost is almost zero.
With this method, you can immediately take the ammonia up to lethal levels far past what any fish could survive. As a result, the bacteria develop and reproduce very quickly, and in a much shorter time, you'll have a far stronger colony capable of supporting a robust population of desirable fish.
When I did it, after only 14 days the bacterial colony in that little 5-gallon tank was fully metabolizing 3ML of household ammonia each day in about 11 hours. I was very conservative, and carefuly monitored nitrite levels over the next 8 days, while adding daily 1ML maintenance doses of ammonia.
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