Getting started with fish keeping

Welcome to the hobby! We appreciate there is a lot to take in when you first decide to keep fish, so we hope this simple guide will shed some light on getting started.

TANK                 Choose a size that is suitable for the space that you have available in your home or appropriate to the type and number of fish you plan to keep. If you are unsure, ask one of our team for advice. The larger the volume of water, the easier it is for you to keep your fish healthy because the water chemistry is more stable. Choosing an aquarium smaller than 30 litres will drastically limit the type and quantity of fish you can keep.

FILTER Every tank needs one! The filter circulates (and oxygenates) the water;      physically removing the fish waste and uneaten food by drawing it through a series of sponges. ‘Good bacteria’ in the sponges break down this waste into harmless by-products, and purify the water. Without a filter, the tank water will become cloudy and stagnant, and fish will gasp at the surface, become ill and usually die.

HEATER Room temperature is approximately 20°C which is ideal for ‘coldwater’ but if you plan to keep tropical fish you will need a heater to warm the water to 26°C.  Don’t forget a thermometer if you choose tropical fish because this shows you the actual temperature of your water and reassures you that your heater is working properly.  Some fish like temperate or sub-tropical conditions so would need a heater set to 22oC.

GRAVEL Ideally choose gravel that has a grain size of 2-3mm (which is best for growing plants). Finer gravel or sand will compact and cause the plant roots to rot, and will be sucked up your gravel cleaner. Larger-grade gravel will not encourage root growth and will trap debris and uneaten food, which will then pollute the water and cause algae. Some gravel (e.g. pea gravel) contains limestone and can make the water alkaline and raise the pH to 7.5 or higher, which can be very dangerous for some fish.

GOOD BACTERIA Use a product that contains dormant bacteria to colonise your filter sponges so the fish waste can be broken down quickly and not pollute your water. You can also use a product with live bacteria to jump-start maturing the filter in order to add fish to a new system sooner, rather than having to wait for the cycle to start up naturally.

CONDITIONER Our tap water contains chlorine, chloramines and heavy metals which cause irritation to fish and kill the beneficial bacteria in the filter.  Use a water conditioner or de-chlorinator to remove these and make the water safe for your fish.

TEST KITS It is really important to keep your fish in optimum conditions, so you will need a selection of test kits. The two most important parameters to test are pH and Nitrite. The pH is a measure of how acidic or alkaline the water is, and most tropical fish prefer a     neutral pH of 7. Most cold water fish prefer slightly more alkaline water of 7.2-7.5. Nitrite is a by-product of fish waste (ammonia) decomposing and is toxic to fish -  levels can peak  after adding new fish while the filter bacteria struggles to break it down safely (no new fish can be added while the levels are high).  You should test the nitrite and pH levels at least every 2 weeks and certainly before adding any new fish.

PLANTS These not only improve the aesthetics of the aquarium, but oxygenate the water, use up waste products, compete with algae, and provide the fish with cover and an alternative food source. Fish in natural-looking planted aquariums are more confident and     relaxed; and therefore usually more colourful!

DECORATIONS This is personal choice: you can use natural wood/rocks, or artificial plants and resin ornaments—as long as you have plenty of interesting things for your fish to explore, they will be happy!  The taller the decorations, the more confident the fish will be: they feel safe and protected if they know there is somewhere to hide from danger.


  1. Find a flat, level site for the tank, on a surface strong enough to support the weight when full of water. Remember that 1 litre of water weighs 1kg, so if you have a 50 litre aquarium you have 50kg of water as well as the weight of your gravel and the actual weight of the aquarium! These days, most tanks are supplied with a plastic support trim, but if your aquarium just has bare glass at the bottom, cushion it with a sheet of polystyrene. The tank should be set up away from direct sunlight to reduce the amount of algae that will be able to grow and to stop it from overheating in the summer. It should also be near electrical sockets: a tropical tank will need 3 sockets (for the light, heater and filter) and a coldwater tank would need 2 sockets (for the light and filter).
  2. Rinse the gravel in normal tap water to remove any dust etc. This should prevent the water from going cloudy when you first set up the tank as it will remove all of the fine dust particles. Add the gravel to the tank, making it deeper at the back to allow for  larger background plants with deeper roots.
  3. Fill the tank with tap water, then use a dechlorinator to remove the chlorine. A common misconception is that tap water should be boiled or left standing to remove the chlorine.  This is a very slow way of doing things (and expensive if you’re boiling your 3000W kettle every few minutes!) and it doesn’t actually remove the heavy metals found in some tap water, so we always  recommend using the conditioner to guarantee instantly safe water. Add bacteria to kick-start the filter.
  4. Add the live plants next, positioning smaller ones towards the front and taller ones at the back of the aquarium. Add any other ornaments and decorations until you're satisfied with your aquascape. Be careful as some natural rocks can affect your pH and water chemistry—ask if you’re not sure.
  5. Set the filter up in the corner of the tank (if it isn’t already built into the system), positioning the outlet so it is just rippling the surface of the water. This makes sure that enough oxygen is diffusing into the water to keep the fish healthy but without causing  excessive algae growth. If you are setting up a tropical tank, add the heater, making sure that it is fully submerged and set to 26°C. (Always unplug the heater to allow it to cool before doing any maintenance or lifting it out of the water).
  6. Ideally wait at least 3 days to allow the water chemistry to stabilise and monitor the pH and nitrite levels. If your water tests are correct, you can add your first hardy fish - ask us for advice about which are the most suitable candidates!


MAINTENANCE & FEEDING For the first 4-6 weeks do not change the water or wash the filter sponges, just allow  the bacteria and water to mature. Only feed the fish in tiny portions, or the filter bacteria won’t cope with the excess nutrients and the nitrite  level will rocket! It is best to feed a tiny amount twice a day - this makes sure that your fish get all of the nutritional benefit from the food without adding too much waste to the tank.  Just like us, fish would prefer to eat little and often rather than being starved for 2-3 days between large meals!

Never change more than 30% of your water volume at once, and clean your filter sponges in a bucket of aquarium water (not under the tap as the chlorine will kill all the bacteria you’ve worked so hard to grow!).

Test your water frequently– you can always bring a sample in for us to test if you’re worried about anything—we do this for FREE as it’s so important!


Got questions? Talk to us :)             01423 869590

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