For the aquarium itself, you should try to find one that is around 20 gallons (76 L) in size. This may seem large for your new fish, but remember, it will grow over time. Fish bowls, contrary to popular belief, are absolutely lethal to goldfish and will decrease your fish’s life span by multiple years. You will need both a water filter and an air pump. Sometimes these are combined into one device. You will also need to buy filters for the water filter itself. Additional items will include a stand and cover for the tank. These help keep the fish safe and secure in its new home. Make sure you find a compatible UV light for the tank. This is important because not all reptile UV units are safe to use near water. Some filters or covers come with a light built in. However, if your cover doesn’t include a light you will need to add a separate one. Run the light for 12 hours a day. Inside the tank you will want to place both sand, along the bottom, and then decorations to sit on the sand. Gravel and larger rocks can be dangerous as goldfish may accidentally swallow them and possibly perish. Also, the larger gaps between pieces of gravel trap poop which is quite unsanitary for your new pet. Finally, you will want to purchase fish food. These are found in pet stores and usually come in the form of flakes.

Wash and rinse the tank, decorations, and gravel to make sure they are clean. Don’t use any soap or detergents. Put the aquarium in a safe and stable place in your home. Once you fill the tank with water, it will be very heavy. So, make sure to select a location where you’d like to house the tank long-term. The surface you set the tank on should also be stable and strong enough to hold the tank when full of water.

Place the gravel first, covering the bottom of the tank. Add your decorations next. Have fun making the tank look interesting to you.

The water should be room temperature, around 65° to 75°F. Add a dechlorinator to the water to remove harmful chlorine from the water. [3] X Expert Source Doug LudemannProfessional Aquarist Expert Interview. 27 August 2019.

Your filter will help keep the water clean and free of waste produced by your fish. Air pumps, and some filters, will add oxygen to the fish’s water, which it needs to breathe.

Add 2 cups of tank water to the bag that your fish is in. Add another 2 cups of tank water to the fish’s bag every five minutes. Stop when you have added 8 cups of tank water to your fish’s bag. If you want to (and can), you can use drip acclimation for about 30 minutes to an hour. Carefully net your fish and add it to the tank. Dumping the fish and bag water into the tank can also dump any waste the fish may have released.

Carbohydrates can be provided by some aquatic plants. Most sources in prepared fish food come from wheat, oats, soy beans and rice. Oils and fats are necessary in your fish’s diet. Try to provide food with a range of 3-10% fat content, as too much fat can cause health problems. Protein is used to repair and maintain tissues and cells in the body. Most fish flake formulas include protein from other fish, shrimp, algae or soy beans. Your fish will also need small amounts of vitamins and minerals.

Feed your fish twice daily, once in the morning and once in the evening. Feed your fish only what it can fully consume over the span of three minutes. [6] X Expert Source Doug LudemannProfessional Aquarist Expert Interview. 27 August 2019.

Keep the water oxygenated. Despite living in water, your fish still breathes oxygen. You will need an air pump and an air stone for your tank in order to oxygenate your water. Adding plants can help as well. Some water filters will have an air pump built in. If yours does, you won’t need to buy a separate air pump or air stone. Monitor the temperature of the water. Fish are unable to control their own body temperature and rely on the temperature of the water to survive. Place the tank in an area that keeps the water temperature at between 65° to 75°F. The final level that needs to be maintained is the pH level. The pH level lets you know how acidic or basic the water is. Usually this level is the least of your worries, so check that every other parameter is acceptable first. Your fish will do best with a pH between 6. 5 and 8.