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Keeping an aquarium can be a wonderful and rewarding experience. Studies have shown aquariums can have a therapeutic effect, such as lowering blood pressure and reducing elevated heart rates and stress levels. This is often why aquariums are popular installations in doctors’ surgeries, dentists and schools. Research in 2017 showed roughly 10% of UK households kept fish as pets. This puts fish behind dogs (24%) and cats (18%) as the third most popular pet animals to keep.

Fish are sometimes classed as a low-maintenance pet to keep and, while this may be true, when compared to other pets like cats and dogs which require regular walking, grooming and trips to the vets (as well as cuddles and playtime), you should still ensure that you have the time, budget and understanding necessary to keep the aquarium and its inhabitants healthy.

Aquarium Basics - Shape, Size & Positioning

A visit to your local aquatic retailer will give you the chance to browse the wide variety of aquariums offered for sale. In early fish keeping days, square or rectangular glass aquariums were all that were available, and the surface area between water and air was important for gas exchange. With the improvement of manufacturing in the last 20 years, along with innovative forms of aeration and filtration, there is now a greater variety of shapes and sizes offered. Aquariums now range from the traditional “glass boxes” we know and love, to those that fit into the corner or a room, or bold tall column aquaria, many with aeration and filtration seamlessly integrated to the point of being invisible. Even the classic, yet controversial bowls have been given a technology boost with integrated aeration and filtration, preserving the style, but making a much more adequate environment for fish.

After the shape is chosen, next comes size. The larger the aquarium size, the greater volume of water it can hold. In smaller aquariums, water parameters generally fluctuate on a greater scale. This variability of water quality is not healthy for the fish and can lead to stress and disease. It is therefore recommended to buy an aquarium as large as one can fit at home and afford. Any hobby should be within the hobbyist’s budget, and with the great variety of aquariums on offer there is usually something for everybody.

The new hobbyist’s fish choice should also have an influence of what size aquarium they choose. A prospective fishkeeper should not only make choices based on the size of the fish they see in the shop, but also take into account the fish’s adult length. Small goldfish and fancy goldfish, the latter which have a tendency to stay smaller, should be given at least 30 litres per fish. Standard goldfish do have the ability to become quite large, so in due course, adult goldfish may need in the region of 90 to 100 litres per fish.

Tropical fish species have a greater variety of size, with some tetras growing to only 1-2cm whilst some catfish species can grow to more than 200cm. Most aquatic retailers will advertise the maximum size of species offered for sale. Remember the smaller the tank size, the harder the water parameters are to keep steady. An aquarium of 60x30x35cm, which would hold approximately 60 litres, is a good beginner size for a couple of small goldfish or a tropical setup.

The placement of the aquarium in the home should also have some thought. An aquarium should not be positioned:

  • in direct sunlight (which can cause nuisance algae)
  • in an area with high footfall (excessive vibration can stress fish)
  • in a room with a high variability in temperature, such as a conservatory
  • near a radiator
  • near a speaker or sound system

Most modern aquariums incorporate a floating base where the bottom glass panel of the aquarium is raised up in a frame, so should not sit on a soft surface (polystyrene or carpet). Some aquariums lack this feature, so should be placed on polystyrene tiles to prevent imperfections in the supporting surface creating pressure points on the bottom of the tank.  Many aquarium manufacturers will require using their cabinets to not invalidate any warranties. Always make sure you know which type of aquarium you have before filling. Finally, the aquarium should always be level to prevent any stress on the glass.

The weight of water is often underestimated and once the aquarium is filled with water and décor, it can be surprisingly heavy.  A 60-litre aquarium, including gravel, water and the glass could weigh in excess of 80 kg (12.5 stone!)  Always make sure that the supporting surface can adequately handle the weight.

Life Support Equipment

To maintain an aquarium, a variety of equipment is needed to keep the water healthy and in good quality. Aquarium filters can be inside the tank (sponge, undergravel, internal) or sit outside (canister, hang-on or sump). Their fundamental job is to grow beneficial bacteria, which convert fish waste (ammonia & nitrite) to less harmful substances through the nitrogen cycle. Some filters also utilise mechanical and chemical filtration, increasing their versatility and efficiency. Filters need regular maintenance to remove excess waste from the filter media. Dirt in sponges block bacteria from growing and this lowers the efficiency of the filter. Aquarium filters are usually rated to provide guidance on how much water they can keep clean, this rating will usually be for a medium-stocked aquarium.  If the aquarium is over-stocked or contains messy species, such as goldfish or cichlids, increase the filter capacity by 50%. It’s difficult to “overfilter” your aquarium and generally the more filtration the better; it’s about striking the right balance between cost and efficiency. Larger filters will move water around with more force, which some fish may enjoy, but some species do prefer calmer water. 

If the aquarium is for tropical fish, an aquarium heater is required. These are usually adjustable between 20-34°C to allow for different tropical environments. Some species, like discus, need temperatures at the higher end, whilst more temperate fish prefer the lower end. Always check the true temperature of the water with a separate thermometer, placed at the opposite end of the aquarium to the heater. As a general guide, heater selection is often based on 1 watt of electricity per litre. A 200-litre aquarium would therefore need a 200 watt heater. This guide assumes a temperature increase of 4°C above room temperature. If the room is particularly cold, or the temperature needs to be higher, a larger heater may be required. The heater should be positioned at an angel of 45° to prevent warm water rising straight up and shutting off the thermostat prematurely, and ideally in an area of good flow.

Aquarium lighting is an ever-evolving market. The latest technology has made huge improvements in output and efficiency. Aquarium lighting can be simply to illuminate the aquarium to view the fish, to vast arrays of LED lights to grow demanding plants or corals. Most aquarium set ups will include a basic form of lighting, but many will offer the ability to increase or upgrade the setup. Consult your local aquatic retailer on what lighting is recommended for your particular setup, bear in mind that too much light could cause you problems down the line with algae growth.

Air pumps increase surface agitation, which in turn increases the amount of oxygen in the water. They are particularly useful in heavily stocked tanks or aquariums run at a higher temperature (warmer water can hold less oxygen than cold water). Air pumps in planted tanks are generally not advised. Too much surface agitation dissipates CO2 which the plants use for photosynthesis.

Aquascaping the Aquarium - The Art of Recreating Nature vs Underwater Castles

Fish are not fussy about how their homes are decorated, as long as there is something to make them feel safe and comfortable. This can be in the form of a natural looking aquascape, with wood and rocks and real aquatic plants, or can be more artificial with themed resin ornaments and brightly coloured gravel. Some tropical fish species, such as catfish and loaches, will prefer a sandy substrate due to their delicate skin and barbels. It is worth noting some natural materials (e.g. wood and limestone-based rocks) can alter the water chemistry of the aquarium. Natural tannins in wood can stain the water and lower pH levels. If clear water is preferred, the addition of Activated Carbon to the aquarium filter will strip out any colourants, heavy metals and smells from the water. If the bogwood decreases pH and KH to low levels, KH up, pH Stabiliser will help restore these parameters to safe levels.

Real aquatic plants will benefit from a suitable substrate, efficient lighting and the addition of liquid fertilisers. NT Labs produce two liquid treatments to enhance plant growth –  Plant Boost & Liquid CO2 Boost.

Water Chemistry

Now the aquarium is home and aquascaped, it’s finally time to add the water. For most freshwater aquarium setups, normal tap water is suitable with one caveat: water companies routinely add chlorine and chloramines to the water for our benefit to ensure that our drinking water is free from pathogens. Chlorine will not only kill the friendly bacteria in the filter but will also irritate and stress the fish. Tap Water Safe is a dechlorinator that removes these chemicals and heavy metals present in tap water whilst also providing a protective coating to reduce fish stress. Dechlorinators should always be used on freshly drawn tap water prior to adding to the tank if fish are present.

To speed up the cycling of the aquarium filter, Filter Starter is a beneficial blend of friendly bacteria which helps ‘kick-start’ the nitrogen cycle, lowering the risk of new tank syndrome (NTS) when the first fish are introduced. NTS is when the bacteria in the filter aren’t yet able to cope with the ammonia being produced by the fish, left unchecked the ammonia levels can become toxic. The Aquarium Starter Kit includes both Tap Water Safe & Filter Starter to effectively set up an aquarium of up to 150 litres at the same price as a single treatment.

Regular testing of the water will provide accurate readings of important parameters. Aquarium Lab Multi-Test Kit provides testing for the 6 key parameters (ammonia, nitrite, nitrate, pH, KH & GH). During the first few months of a new aquarium, the water quality will fluctuate as the filter matures. Once the aquarium has fully cycled, the focus on testing will be to make sure pH and hardness do not drop too low (which could be an indicator of insufficient maintenance). For more in-depth knowledge on water parameters and testing, check out the article in the Knowledge Hub.

Introducing the First Inhabitants

Adding fish to the aquarium has got to be the most anticipated moment of starting an aquarium, but it should not be done in a hurry. Aquariums should be left for at least 5-7 days prior to adding any fish to allow the water to settle and reach the correct temperature. This also gives enough time to observe any possible defects in the equipment before it poses a risk to the fish. Remember, new aquariums are prone to NTS (New Tank Syndrome) and this usually occurs if too many fish are added to an immature aquarium. Cycling of an aquarium can take upwards of 10 weeks so caution and patience should be applied during this time. Your local aquatic retailer will usually advise you on the quantity and species of fish to add based on the size of your aquarium but also on the set-up you are looking to achieve. For example, although members of the “danio” family are generally regarded as being ‘hardier’ and therefore a good first addition, there’s little point if you are wanting to keep African cichlids or Discus, neither of which would be a suitable set-up for danios.  It’s important to know what type of set-up you want at this point and to have done as much research as possible.  Your local aquatic retailer can further advise you based on the information you provide so, the more you know about your set-up (size, filtration, water parameters etc.), the more the retailer will be able to help you.

Once the fish have arrived home, it is important to acclimatise them safely into the aquarium. Although many hobbyists have different methods, a good all-round method observed below:

  1. Turn out the aquarium lights and dim the room, if possible.
  2. Float the fish bag on the water, without opening, for 15-20 minutes. This equalises the water temperature of the bag with the aquarium.
  3. Open the fish bag and roll down the sides of the bag to create a floating ring.
  4. Add a small amount of water to the bag, either quickly dipping the bag in to the aquarium, or using a cup. Repeat every 5-10 minutes for at least 30 minutes. This equalises the chemistry of the fish bag water with the aquarium, such as pH and hardness. This is done slowly to give suitable acclimatisation time, as large changes in pH should always be avoided to lower stress levels on the fish. The fish should be closely observed throughout this time for signs of oxygen starvation which can be identified as gasping or becoming unstable in the water.  If this occurs, then additional aeration should be added to the bag by way of an air stone if available.  Alternatively, you may have to add the fish to the aquarium a little quicker than planned!
  5. In most instances, the bag should then be tilted and the fish allowed to swim from the bag into the aquarium.  In other scenarios, it may be necessary to ensure that the water in the bag does not enter the aquarium. If this is required, use a net to carefully lift the fish out of the bag and gently place them in the aquarium.  The bag and water contain can then be discarded.
  6. Add Tap Water Safe after any new additions; it contains a special protective coating agent which helps reduce stress on fish after transportation.
  7. The lights can be turned back on after several hours. Don’t be surprised if the new fish do not feed and hide away for the first day or so, as they may still be nervous in their new environment.

Regular Maintenance Routine

An aquarium needs regular maintenance to stay healthy. Maintenance schedules can be divided up into daily, weekly and monthly.


  • Feeding - recommended to be done two to three times a day to help recreate a natural feeding regime for the fish (once your aquarium is cycled, in the first 6-8 weeks once a day or even once every other day would be recommended. In the wild, fish continually search for food. By being offered food at different times this will aid their natural digestion times. Be careful not to overfeed, only feed as much as the fish consume in a few minutes, remove any uneaten food after this time and adjust the amount you feed next time accordingly.  Overfeeding will lead to excess waste and poor water quality.
  • Health check of the fish - are they all behaving normally? Signs to look out for are: loss of appetite, ragged or clamped fins, staying in one location or hanging around the filter outlet, cloudy eyes, parasites or red blotches. If something is not looking right the first port of call should be to check your water quality. If all is well, check out our diagnosis tool for help with which medication is most suitable.
  • Visual check of the equipment - is the filter running as normal? Is there suitable movement at the water surface for good oxygenation? Is the temperature of the water within the suitable range?


  • Performing a partial water change in the aquarium. Hobbyists have individual routines, but a good recommended amount to change is approximately 25% weekly. Using a gravel cleaner syphon to drain the water will also help disturb the substrate and lift any uneaten food and other detritus from decomposing in the substrate and creating excess waste. Replacement water should always be treated with Tap Water Safe to remove chlorine, chloramine and heavy metals prior to being added.
  • Cleaning the aquarium glass using a myriad of glass cleaners. There are algae pads, pads on sticks, magnetic algae cleaners and even ones with metal blades.  Please consult with your local aquatic retailer who should be able to advise you on the most suitable tool for your aquarium, care should always be taken to ensure you don’t trap a piece of gravel or sand between the glass cleaner and the glass as this can result in the glass becoming scratched.
  • Water testing - this is usually recommended to do before any cleaning to give a better understanding of the quality of the water. Testing immediately after a water change can give false readings and will not give a true representation of the aquarium’s water chemistry.  You should keep a record of your results to allow you to spot any patterns and adjust your maintenance routine if necessary.


  • Filter maintenance - Usually monthly but depending on your stocking density or particular brand of filter, may be more frequent. Most aquarium filters consist of mechanical, chemical and biological filtration. The mechanical filtration is usually sponge, and this is what is expected to be cleaned. Never wash filter sponges in tap water! The chlorine and cold temperature of tap water will kill any beneficial filter bacteria living in the sponges, destroying the biological filtration. Doing so may cause similar symptoms to NTS, even in mature setups, so always clean the sponges in aquarium water (the water removed at a water change is fine, remember the sponges don’t need to be spotless, just unclogged). Some chemical filtration may need replacing as they often have a ‘fixed’ useful life span before they stop being effective. It is recommended to always add Filter Starter after filter maintenance to aid in the repopulation of the biological filtration.
  • Whilst performing filter maintenance it is recommended to check the moving parts of the filter, namely the impeller. By removing and cleaning the impeller, it can improve flow rate, prevent clogging and extend the life of the motor. Most ‘broken’ filters returned to stores are usually impeller related and are easily rectified. If the filter is a canister style external filter, it is good practice to remove the rubber o-ring from the motor head, wash and re-lubricate to prevent potential leakages.

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