Yes! Since the cycling process can cause some stress on your fish, there's lots of ways to add ammonia to your system without introducing them first. There's various 'cycling kits' that can be purchased online, giving you ammonia or other powdered additives to start processing the nitrites within your system. Once the ammonia and nitrites have dropped almost to zero, you should be able to start measuring nitrates. This is a sign that the bacteria needed to convert ammonia and nitrites are healthy and functioning as they should.
While adding fish is a natural way to add ammonia into your system thruogh waste, it's possible that the water can become toxic for fish if the nitrifying bacteria doesn't establish itself quickly enough. Fishless cycling prevents this, while still establishing a healthy bacterial base for your system.
