As with everyone beginning a new hobby, mistakes are easy to make, so starting by keeping coldwater fish is a good way to learn: they are hardy and easy to keep. This advice is general in content, for specific queries re your own circumstances, location of tank, breed of fish etc, please contact an expert in person.
Remember, that water provides fish with the oxygen they need to live. The amount of oxygen contained in water is directly related to the quality of that water: dirty water has little oxygen in it.
In an aquarium, waste products (ammonia) from the fish can build up, polluting the water and reducing the oxygen available. Plants and filters help to break down and remove waste products from the water. This is known as the nitrogen cycle - and it is essential to establish this before you add the fish you have chosen.
What do l need to get going?
Tank: The ideal size is 136 litres, if this is beyond you then don't go any lower than a 45 litre RMcapacity. Larger tanks are easier to keep as a stable environment, and you can keep more fish. Attractively shaped tanks are very nice, but the best type to maximize your stock is long and wide. The surface area governs the amount of fish you can keep in your tank; 125 square cm of surface area will support 2.5cm of a deep-bodied fish.
Stand: You're going to need a stand that will support its weight, keep it level, and can't be toppled over. If it's a narrow stand, it should be fixed it to a wall.
Lights: Great lighting shows off your fish and is essential for plants. However, there is a down side: light makes algae grow which means more cleaning for you. In addition, some fish don't like bright lights. There are special fluorescent lights available which emit very little heat and provide light at the correct wavelength for plants.
Hood: A tight fitting hood will stop your fish jumping out, stop unwanted visitors such as a cat getting in, and provide a covering for your lighting system.
Thermometer: Is a useful instrument to make sure your coldwater fish don't get too hot.
Maintenance tools: At the very least, you're going to need a net, tank scraper, a siphon, and a bucket.
Filter: Every fish tank must have some form of biological filter to remove waste products (especially ammonia) and debris. There are numerous good biological, chemical and mechanical filters on the market. The under gravel method is one of the most popular.
Gravel: It is preferable to buy pre-washed gravel from a pet store. Gravel from other sources will have to be washed and then boiled for 20 minutes, and if you don't know what type of stone it is, your tank's pH levels could be affected. It's a good idea to rinse pre-washed gravel again yourself. Some gravels are plastic coated for easy cleaning - these should not be boiled!
Decorations: There are lots of these to choose from! Read the labels carefully in case you have to boil the decoration before adding it to your tank.
Plants: Make sure you buy your plants from a good store. Check that they are compatible with the fish you intend to keep, and that they won't grow too fast.
Air pump: The air pump circulates air around the tank and increases the rate of absorption of oxygen at the water surface. There are many different kinds to choose from.
Essential test kits: To keep a check on the water quality in the tank you'll need ammonia, nitrite, nitrate and pH testing kits.
Chlorine treatment: Many water companies add chlorine and chloramines to your tap water but fish don't get on well with either of these. Fortunately, there are several good products to treat your water for these chemicals.
Starter kits and starter fish: To start of the nitrogen cycle in your tank, you need a source of ammonia. This can be achieved in two ways: you can buy a starter kit that will add ammonia to the water; or you can add one or two hardy fish that will excrete ammonia into the water (called starter fish). Goldfish are the best starter fish for coldwater tanks: you will need one goldfish for a 45 litre tank and two goldfish for a 136 litre tank. Do not add many more fish until the nitrogen cycle in your tank is established! (see: Starting the nitrogen cycle below).
Putting it together
Place your tank securely on its stand in its final location. It's best to choose an area of the room that doesn't get too much direct sunlight because algae love sunlight.
Start adding medium-sized gravel (that has been washed according to the instructions), building it up from the back of the tank. If you have an under-gravel filter install this now, following the instructions. The gravel layer should be thinnest at the front of the tank.
If you have a power filter, install it now so that the tubing runs along the length of the tank.
Next, arrange your decorations and plants. Leave the plant and root junction showing above the gravel.
Using pre-treated water fill the tank to about two-thirds, and adjust the plants and decorations if necessary. Then, fill the rest of the tank, install your thermometer, and prime your filter by following the instructions on the packaging.
Your starter goldfish is next. Float the bag it's in on the surface of your tank for about 30 minutes. Then open the bag and allow the fish to come out and explore. This is your source of ammonia for the tank cycling to start.
Finally, if you've bought lights and a hood, install them now.
Starting the nitrogen cycle ('cycling the tank')
Before you stock your tank fully, you need to establish the nitrogen cycle in the tank. This means that any waste products (e.g. ammonia) in the tank are broken down by the plants, filter and bacteria in the water.
Your starter fish or start kit is the source of the ammonia. If you use a starter fish do not overfeed it!
Test the water levels regularly over the next few weeks. The nitrogen cycle is working when the ammonia and nitrate levels are zero. For a coldwater tank, this can take six weeks and longer. There are safe products that you can add to the water containing bacteria that can speed this process up safely.
Do not add any fish until you are sure that the tank is cycling naturally. ENJOY!