Instructions
Understand the nitrogen cycle that your freshwater tank will go through. When you add fish to a new tank, they eat, then they produce waste. The waste they produce is high in molecules containing nitrogen, the most toxic of which is ammonia. In an established tank, "good" bacteria eat the ammonia and other nitrogens, but a new tank doesn't have enough probiotics to keep up with all of the waste. This can make some delicate fish very sick.
Choose freshwater fish that are ammonia- and nitrogen-tolerant to stock your tank until colonies of "good" bacteria mature. Many barbs, including tiger barbs, work well because they're inexpensive and hardy. Catfish, tetras, guppies, mollies and platies are also hardy and good starter fish.
Select starter fish that you'll enjoy watching while your tank completes its nitrogen cycle, approximately four to eight weeks. You might want to purchase inexpensive ones because starting a new tank is always risky.
Buy groups of six or more of the same type of fish to start your tank. Add new fish one or two at a time after testing for nitrogen in several weeks.
How to Choose Starter Fish for Freshwater Aquariums
When you're trying to establish a healthy freshwater aquarium, it's important to stock a new tank with appropriate types of fish. The more expensive a fish is, the more delicate it tends to be, so buy some inexpensive starter fish to get your tank through its nitrogen cycle. Follow these steps for choosing your starter fish.