My first Fish Tank



Getting started with tropical fish is easy, provided you do a little research on how to keep tropical fish in advance. Our 10-step how to guide introduces the key decisions.

You could also ask for help at a decent aquarium store, but you’ll get a much better understand if you understand the basics first.

Think through what you want to achieve and then proceed patiently, rather than just rushing to the local fish store this afternoon and leaving with a bruised credit card and a car full of fish kit.

Not all tropical fish can be kept together. Some are aggressive, others have special water requirements, but there’s hundreds of species that do happily get along.

Community fish: Most of the smaller fish like tetras, guppies and corydoras catfish that you typically see bustling about in one aquarium are called community fish. A tank of them with plants looks beautiful, is affordable, and gives you plenty of choice in the store, making community fish the best way for a new aquarium keeper to start. (The cardinal tetras above are from Leino88).

Specialized fish: About 10% of the freshwater fish you see in a tropical fish store require specific care requirements. Discus, African Rift Valley cichlids, killifish, certain catfish, and oddballs like Elephant Nose fish need tanks with particular water conditions or environments. Others, like pirahnas and many Central American cichlids, are flat out incompatible because they’re too aggressive.

Tank busters: Some fish are tough and friendly enough to anything they can’t swallow, but they grow far too big for the average aquarium. Pacus, Giant Gouramis, and many big catfish fit into this category. These fish are less readily sold than in the old days, which is good news, as too often they outgrew aquariums and were dumped in the natural environment (a big no-no). Best left to specialists.

Marine fish and invertebrates: Require more dedicated and knowledgeable care. This how to is only for freshwater fish, which originally came from the rivers and lakes around the world. (Marine fish come from the sea and so require special salt, as do certain brackish water fish like Scats and Archer fish).

Plants: Tough plants like Amazon Swords will grow in almost any aquarium if given some light and gravel to root in. But if you want to have a really lushly planted aquarium, you’ll need to plan from day one to give your plants the light, substrate and water conditions they require to thrive.

Decide how big an aquarium you’ve room for

Next you need to decide how big a fish tank to get, depending firstly on the room you have in your house. Water is heavy, so anything other other than a tiny aquarium requires its own special stand, either bought or home made. With really big aquariums, you may even need to check the floorboards.

You’ll also need to make sure it’s not too near your central heating or a window, both of which can overheat the tank, and it’s a good idea to avoid draughty spots, too. Electrical sockets nearby are a must for tropical tanks.

The size of the aquarium determines how many fish you can ultimately keep. Fish require oxygen and clean water, and so any volume of water can only support so many fish before they start to suffer.

A typical 24? inch by 12? Fish tank will happily hold about a dozen 2?-sized tropical fish.

Choose your filter system

An external filter sits outside of the aquarium

There are lots of different filter systems available, but for freshwater tanks you have four main options:

Under gravel filter: This sits beneath the tank gravel, filtering the water biologically by building up a population of bacteria in the substrate, and also straining out particulate debris. Water is moved through the gravel via a filter plate attached to airlifts, powered either by air pumps or powerheads. An easy way to start, but not great for plants and can be messy to keep clean.

Internal filter: Small internal filters can cost as little as the price of half-a-dozen community fish. Internal filters typically have a sponge inside, which filters the water and builds up a population of bacteria that keeps it sweet. Very cheap models are driven by an air pump; they’re effective, though the bubbles and pump can be noisy. Internal filters a very affordable option for small aquariums. But against that they take up tank room, and can be ugly.

External filter: These sit outside the tank, usually in the cabinet below but sometimes hanging off the back. They come in all shapes and sizes, and range in price from a little more costly than an internal filter to the price of a portable TV! The best enable you to use several different types of filter media inside them, and they move a lot of water, making them great for bigger tanks. One snag can be leaks outside of your aquarium if a pipe comes loose. They can be expensive, but a big advantage of external filters are they’re easier to maintain without disturbing your tank furnishings.

No filter: It’s possible to use no filter, keeping the tank water clean with plants, the natural way. It does work, but there’s little room for error, especially if you fill the tank to maximum capacity. Water looks nicer when it’s moving, too, which means at least getting an air pump. A filter-less tank is not recommended for beginners.

Buy all the equipment – but no fish yet!

Once you’ve decided on your tank and an appropriate filter, you can start buying all the equipment you’ll need. The essentials are:

¦The tank and stand

¦A lighting system that either sits inside the aquarium hood or is mounted above it

¦A good quality heater-thermostat, for keeping the water at tropical temperatures

¦A thermometer that sticks on the glass

¦A net for catching fish

¦An air pump (optional, unless used to drive an under gravel filter)

¦Gravel (a good layer is vital if using an under gravel filter) or special aquatic soil for growing plants

¦Furnishings to make a natural home, such as decorative bogwood and suitable rocks. (Plastic castles and treasure chests are strictly down to personal taste, but do make sure anything is made specifically safe for long-term aquarium use)

¦Water treatments for neutralizing chlorine in tap water

¦Basic test kits for Ammonia, Nitrite, Nitrate and pH

¦A few fish disease medicines (get them before you need them!)

¦A small separate aquarium for quarantining new fish is a great bonus

Set-up your aquarium in its permanent position


This empty tank has filter, substrate and wood nicely positioned.

Get the tank in position and set up according to the manufacturer’s instructions (it will probably need a layer of polystyrene under the bottom glass, to prevent cracks). Don’t try and move even a small aquarium once it’s got any water inside – fishtanks are very heavy, and even if you can pick it up the glass will likely break.

It’s a good idea to fill the tank straight away to check for leaks. Put the tank in its final position, then direct a hosepipe into it until it’s filled. Check all the corners and sides of the aquarium for leaks. You’d be very unlucky to have a new tank leak, but secondhand tanks sometimes develop leaks from being moved. If your tank does leak, you’ll have to drain and thoroughly clean it, then rework the seal using silicon gel. If the tank is new, get the store to fix it.

No leaks? Great. Syphon out all the water, then put the equipment in place. Filter pipes are best tucked into the corners. Heaters are best attached to the glass at a 45-degree angle, so rising heat is whisked away from the thermostat by the aquarium water.

Next add your furnishings and gravel or aquatic soil. Spend some time experimenting to get a look that works. Some people even like to arrange the stones and wood outside of the aquarium first, or sketch it out on paper.

It’s a good idea to hide equipment as much as possible with your tank decorations, but make sure you can see the thermometer and heater light, and that your filter can operate properly and is easily accessible.

Fill the tank with water, and switch everything on

No fish yet, but plants alone give this tank some beauty and interest

What’s an aquarium without water? If you’re keeping delicate tropical fish like discus you’ll want to purify the water first, but for general community fish, it’s generally okay to set-up the tank with tap water, since you won’t be adding any fish for a while and the filters will soon drive out chlorine from the water.

To fill the tank, place a bowl on the tank substrate, then direct water into it, either via a slowly trickling hosepipe or else by pouring buckets of water in. The bowl takes the force of the water, preventing the gravel or aquatic soil from being blown about.

Advanced aqua capers add their plants to the tank before adding any water, but for new fish keepers it’s easier to fill the tank first and add your first tough plants after the water has reached the correct temperature.

Now switch everything on, and make sure all the pumps are working properly. The water temperature should rise to about 25-degrees C (77-degrees F) after a day or so. If it’s too hot or cold, adjust the thermostat.

Wait! Mature your tank before adding fish

Your new tank will look lovely and clean, but the filters won’t yet have built up the populations of bacteria required to break down fish waste. For this reason you need to add fish over a period of weeks, allowing the ‘nitrogen cycle‘ to start operating effectively in your tank.

Maturing the tank with fish: The traditional way to do this is to add a few tough fish like Zebra danios to the tank first. Their waste products will eventually be broken down by the filter bacteria, but it will take a while for it to start happening, which means they will be exposed to pollutants. For this reason, only start with 3-4 fish, and feed them lightly. If you test the water every day for Ammonia, Nitrite and Nitrate, you can track the nitrogen cycle developing over time. Eventually Ammonia will be undetectable in your tank, which is when it’s said to be mature.

Maturing the tank with chemicals: A way to avoid putting any fish through discomfort with a new aquarium is to buy a special product for maturing the tank using chemicals. These products deliberately add nitrogen to an aquarium to get the tank going. You can achieve a similar thing by adding a marble-sized bit of cooked meat. Theoretically the results will be the same, although tanks matured with fish seem more stable in the early weeks. Some products also add bacteria to the water, but don’t worry, bacteria will already be present in the tank, so it’ll only take a few days longer if you wait. Again, test the water – you should see Ammonia rise and then fall away and stay at zero. When Nitrite is also zero, it’s safe to add some fish.

Maturing a natural aquarium: The waste products that are so dangerous to fish are actually food for plants. For this reason, a really well-planted tank can support a few fish just a day or two after the plants are established. However, it still makes sense to go slow, for the sake of your fish’s health. Also, even in natural aquariums, bacteria attached to plant leaves and on the surfaces of the aquarium play a key role in breaking down waste, and these take time to establish.

With all three methods, you can add as many live plants as you like right away, so be patient when it comes to fish and indulge your spending desires on vegetation. Ideally add a lot of plants at the start, to help keep algae under control later (floating plants are particularly good for this).

Slowly build up to your tank’s stocking capacity

A pair of angelfish make a splendid focus for larger community tanks

So, the nitrogen cycle is established in your tank, and your first fish and plants are happy. Don’t rush things, though – patience is a virtue in fishkeeping.

Your tank is always in a delicate balance between the inhabitants and the plants and bacteria that deal with their waste. Add more fish, and you disrupt the balance. Bacteria will quickly multiply to utilize the extra waste the new fish bring, but it does take a few days. Therefore it’s best to build up to your maximum stocking capacity slowly, over a period of several weeks.

Ideally new fish will be quarantined and treated for disease in a small hospital tank so they don’t infect your established fishes. All the books tell you to do this and it is an excellent practice, which will greatly reduce problems with your fish, but in reality most one tank aquarists don’t bother.

Be vigilant when buying fish for any signs of disease (such as flicking, gasping, or any visible spots or irritations) and if in doubt, don’t buy.

As you move towards your tank’s maximum stocking level, try to see the aquarium from the fish’s perspective, to avoid overcrowding any niches in the tank. Don’t only buy surface dwelling fish, or fill your tank with catfish, say. Try and get a nice range of compatible community fish that occupy different layers of the aquarium.

Creating a natural biotype is a good way of planning your stock. With this method you buy community fish from the same part of the world, and decorate the tank appropriately for that region.

For instance, a two-foot, 15-gallon South American biotype might be decorated with bogwood, river sand and Amazon Sword plants, and contain the following fish:

¦4 surface-dwelling marbled hatchet fish

¦8 neon tetras

¦2 Apistogramma dwarf cichlids

¦3 bronze corydoras catfish

Perform your daily, weekly, and monthly tank tasks

Get your hands wet to keep your tank clean

The secret to having a beautiful tropical fish tank in the long-term is to regularly perform the required maintenance tasks, rather then letting things slide and then trying to catch up.

A good routine for a standard tropical fish tank would be:


¦Feed the fish (twice a day)

¦Add plant fertilizer (optional)

¦Check the tank temperature

¦Check for any signs of ill-health


 ¦Top up the water level

¦Trim plants (if required)

¦Clean tank glass of algae

¦Test tank water parameters (especially when the tank is still young)


 Change 25% of the tank water with treated tap water

¦Replace disposable filter media, such as filter floss and activated carbon

¦Clean biological filter media in a bucket of used tank water (which is then discarded)


Replace fluorescent light fittings

¦Consider replacing your heater and thermometer

Enjoy your aquarium!