Here's why:
* The Nitrogen Cycle: The main reason for a "cycle" is to establish beneficial bacteria that will break down fish waste (ammonia, nitrite, and nitrate). These bacteria need time to grow and multiply. While waiting for the tank to cycle is important, it doesn't need to be completely empty.
* Fish-In Cycling: You can actually cycle the tank with fish in it! It's called "fish-in cycling" and involves adding a small amount of fish and carefully monitoring water parameters, making adjustments as needed.
* The "Two-Week Rule" is Outdated: The idea that you need to wait two weeks stemmed from traditional methods of cycling, which involved using ammonia to jumpstart the process. This was often done with an empty tank. However, fish-in cycling is a safer and more efficient way to get your tank up and running.
Here's what you *should* do:
1. Set up your tank: Fill it with water, add your substrate, decorations, and filter.
2. Start the cycling process: You can use a "fish-in" method with a small number of hardy fish, or you can use a "fishless" method using ammonia or a commercially available product to jumpstart the bacteria growth.
3. Monitor water parameters: Test your water for ammonia, nitrite, and nitrate levels regularly.
4. Be patient: It typically takes a few weeks for the nitrogen cycle to become established. During this time, keep a close eye on your fish and adjust your water changes as needed.
Remember: Cycling is crucial for a healthy and happy fish tank, but it doesn't have to be a stressful process. Consult with a local fish expert or research online for more detailed information on cycling methods.