Freshwater aquariums
Keeping an aquarium is an immensely enjoyable and rewarding hobby for both adults and children alike. This guide aims to help you in what to consider when setting up and maintaining a freshwater aquarium and to ensure that your fishes’ welfare needs are met.
What next?
View the information below to learn the essentials for setting up and maintaining a freshwater aquarium.
Take the test, and when you have passed, you will receive a certificate to show to your pet shop and prove your knowledge.
Information for setting up and maintaining a freshwater aquarium
The Pet Know How tests are designed to test your basic knowledge of keeping a pet of your choice. They will help you understand the needs of the animal and some of the important things you need to consider if you were to have one as a pet. Once you complete a test you won’t be an expert keeper but you will be in a better position to make an informed decision and decide if you are able, and willing, to take on the responsibility.
In this section, you will find a wealth of knowledge compiled by pet experts to provide you with the valuable information you need regarding setting up and maintaining a freshwater aquarium.
Work your way through all the sections, and when you feel ready, register yourself to take the test and earn a certificate that proves your knowledge.
Introduction
As a general rule you should, within reason, buy an aquarium as big as possible. Ideally, it should be able to accommodate your chosen fish once they are fully grown. Otherwise, you must be prepared to buy bigger set ups as your fish grow.
Aquarium sizes range from nano tanks through to large custom-built aquariums of much bigger capacities. As larger aquariums contain more water, they will be more stable and less susceptible to variations in temperature, pH etc than small aquariums.
Positioning your aquarium
Once your set up is ready, position your aquarium so it is:
Out of direct sunlight and away from sources of heat or draughts.
On a flat level surface or stand (which can take the weight of a full tank indefinitely).
Away from loud noises, vibrations and sudden movements.
Maturing your aquarium filter
Once your aquarium has been filled and the water has been dechlorinated (either by letting it stand for 24 hours or through use of a commercial dechlorinator), switch on your equipment. It is advisable to leave the aquarium for between 24 to 48 hours to settle. This ensures that the correct temperature is reached (if it is a tropical set up) and that the equipment is working correctly. You will need test kits to regularly measure that the water quality is suitable for fish, these should test for ammonia, nitrite, nitrate and pH.
Your aquarium filter then needs to ‘mature’. Waste products from your fish and any leftover uneaten food contribute to ammonia (NH3) levels, which together with nitrites (NO2-) are highly toxic to fish. However, there are bacteria (known as nitrifiers) which can quickly break down ammonia and nitrite to the much fewer toxic nitrates (NO3-). These beneficial bacteria will not be present in a new aquarium filter, so the process of maturing your filter involves growing a population of these bacteria in the filter media and there are two common methods of doing this: ‘Fish-in’ and ‘Fish-less’ cycling.
Filter maturing methods
‘Fish-in’ cycling
The ‘Fish-in’ method involves adding a small number of ‘hardy’ fish to the aquarium. Note that this method should only be used with great care, and under guidance from your OATA retailer, to safeguard the welfare of your fish. Your OATA retailer will be able to advise on what fish are most appropriate for your aquarium depending on how mature your aquarium is, and the water chemistry of your aquarium.
‘Fish-less’ cycling
The ‘Fish-less’ method involves adding a calculated dose of ammonia to your aquarium over several weeks. You will need to use an ammonia-based aquarium maturation product and follow the instructions included. There are also proprietary bacterial cultures available, which when used as per the manufacturer’s instructions, can help to ‘kick start’ maturing of your filter.
Maturing your aquarium filter continued…
Whichever method you use, ammonia and nitrite levels should initially successively rise and then fall, while nitrate (the end product of filtration) levels will usually continue to rise. It is important if you have added fish, that the levels of these waste products do NOT rise above the guidelines given in this guide. Regular partial water changes will be required as will regular water testing to monitor for any changes and to take action as necessary. Frequency and volume of water changes will depend on stocking levels and other factors: ask your OATA retailer for advice. Once the levels of ammonia and nitrite have dropped to zero and stay at zero continually, your aquarium filter is mature and stocking can continue slowly. Bear in mind, that each time you add more fish or increase feeding, a ‘mini’ maturation process will be required for your filter to allow for the numbers of beneficial bacteria in your filter to build up to deal with the extra amounts of waste produced.
Coldwater/Tropical Freshwater home aquaria
Ammonia (NH3): Zero mg per litre
Nitrite (NO2-): Zero mg per litre
Nitrate (NO3-): Check species specific care sheets
Note: Nitrate levels in tap water can vary widely between different areas. Do seek advice from your local OATA retailer on safe nitrate levels for the fish you keep.
Adding your fish
Before adding any fish, seek advice from your OATA retailer in choosing the type of aquarium you would like to keep and the species you are interested in. OATA has a range of free care sheets which cover the majority of commercially available species. Some fish species need to be kept in shoals whilst other species are territorial and/or aggressive and will not live together peacefully. Different species may also prefer different water types, flow rates etc, and will have a preferred temperature range.
Only increase the number of fish you have in your aquarium slowly as the population of beneficial bacteria established when maturing your aquarium filter need to increase every time more fish are added and feeding increases. Overstocking or stocking your aquarium too quickly can result in ‘new tank syndrome’. This occurs when there are not enough nitrifying bacteria to cope with the increased waste load, leading to unhealthy levels of ammonia and nitrite which may cause fish to become ill or die.
Stocking and aquarium set up
It is not possible to say exactly how many fish your aquarium can hold. The differences in body size, species requirements, water parameters and compatibility of fish available are vast. Ask your OATA retailer for advice on stocking densities for your chosen aquarium and species you would like to keep.
Aim to create a suitable environment for your chosen fish. Remember that decoration and plants take up space but are recommended additions as enrichment for your fish. Live plants help to remove nitrate, and ornaments can provide less boisterous and reclusive fish with a safe retreat.
Do not expect to fill your tank with as many fish as your OATA retailer. They are able to stock tanks more heavily than home aquariums due to their management expertise and advanced filtration systems.
Feeding
Diet and feeding requirements vary between species. Some feed at the surface, others will be found throughout the water column, while others will spend most time at the bottom of the aquarium. Some will also have specific dietary needs e.g. algae eaters, and will need specific foods to thrive. Be sure to have suitable food to cater for all of your fishes’ needs. When starting with fish it is best to pick hardy species which can live together. Good beginner tropical species include tetras, guppies, mollies, platies, swordtails, corydoras and gouramis, but your OATA retailer may have some other suggestions. Species suitable for unheated aquariums can be found in our “unheated aquarium inhabitants” care sheet.
Transporting and releasing your fish
First check that your new fish are compatible with those that you may already own and that the water quality in your aquarium is suitable i.e. levels of ammonia and nitrite are zero. Your OATA retailer will usually sell your fish to you in a plastic bag. Try not to keep them in this for too long. Once purchased, take your new fish home as quickly as possible as fish are easily stressed by bright lights, extreme temperatures, noise and movement.
Once home, your fish will need to acclimatise to their new environment. There are two common methods to do this known as the ‘floating bag’ and the ‘drip acclimatisation’ methods. Switch off aquarium lights and take the bag containing your new fish out of its outer wrappings carefully, avoiding exposure to bright light.
Depending on which method you use, it can take between one to several hours, particularly for more specialised species such as Discus. Once complete, carefully release the fish into your aquarium and dispose of the bag and any excess water appropriately. Monitor your new fish carefully for the first week, paying particular attention to water quality. If in any doubt, contact your OATA retailer for advice.
Fish introduction methods
The ‘floating bag’ method
If using the floating bag method, float the bag in the water of your tank for at least 10 minutes to ensure the temperature in the bag is the same as the aquarium water. Whilst the bag is floating, slowly introduce small amounts of aquarium water into the bag containing the fish for up to 20 minutes. Some more sensitive species might require a longer period of mixing, but your OATA retailer should be able to advise you.
The ‘drip acclimatisation’ method
If using the drip acclimatisation method, proprietary kits are available whereby water from your aquarium is ‘drip fed’ into a container holding your new fish and their transport water, until water conditions are the same as those in your tank. This method is ideal if you are introducing a particularly sensitive species, or if your water chemistry in your aquarium is likely to differ greatly from where the fish have come from.
Maintenance
Your fish are totally reliant on you to keep them healthy, so your aquarium will require regular maintenance. Most tasks are relatively quick and simple:
Check the water quality regularly (at least once a week) to prevent the build-up of harmful wastes such as ammonia and nitrites. You may wish to test more frequently such as when setting up your aquarium and when adding fish. Also take care to regularly check the water is at the correct temperature.
Partial water changes (up to 25% every week) will help remove excess waste chemicals. Before adding new tap water, make sure it’s at the correct temperature and is treated to make it safe for your fish. Frequency and size of water changes may vary according to what species you keep, the aquarium size, the number of fish you have and other factors. If in doubt, seek advice from your OATA retailer.
Check filters for blockages and fish waste build-up. Never rinse them under a tap, since this will wash away and kill the beneficial bacteria, but instead, use some of the waste water from a routine water change to clean filters.
Remember: never siphon water from your aquarium by mouth. Cover any open cuts before putting your hands into an aquarium and always wash your hands immediately afterwards.
A healthy fish should...
Have clear bright eyes
Have undamaged fins
Have intact scales
Have no ulcerations or bumps
Have appropriate swimming behaviour
Have steady breathing
Do not purchase a seemingly healthy fish if sickly fish are present in the tank with it. Some diseases can be easily carried without fish showing any clinical signs. If in doubt, ask your OATA retailer for advice as they will have in-depth knowledge and experience.
What to watch out for
All fish will have slight variations in their behaviour or appearance, but keeping an eye on any changes in the following will help to identify any potential problems before they become a real health issue:
Swimming behaviour – hanging at the surface, sitting on the bottom or erratic swimming
Colour – turning a darker or paler colour than normal
Temperament – changes in level of aggression or hiding more than normal
Breathing – gill covers moving at a slower or faster rate than normal
Appearance – development of white spots or fluffy growths, loss of fins or scales
Condition – increase or decrease in body weight and condition
Feeding – reduced intake or lack of interest in food
If you are concerned about the health of any of your livestock, then test your water quality and contact your OATA retailer for further guidance.
Shopping list
Freshwater aquaria can be used to keep either coldwater species e.g. goldfish or tropical species (which must be kept in heated water) e.g. guppies. The type of set up that you choose i.e. coldwater or tropical, will determine what equipment you need to purchase.
As a general checklist, a freshwater aquarium should include:
Glass or acrylic aquarium with secure lid
Suitable stand
Suitable substrate e.g. Gravel, Sand
Filtration
Air pump
Lighting
Siphon cleaning device
Bucket (for water changes)
Ornaments
Plants (live or plastic)
Heater (for tropical tanks)
Water conditioner/ dechlorinator
Thermometer
Water testing kits (for ammonia, nitrite, nitrate and pH as a minimum)
Food (suited to your chosen fish)
Water testing kits (for ammonia, nitrite, nitrate and pH as a minimum)
Water test kits will help you maintain good water quality for your fish so their purchase should be considered a necessity. Many OATA retailers will offer free water testing services and can provide advice on how to test your aquarium water at home.
Pet code of practice
Owning a pet is a responsibility and owners must always ensure that they act in a way that ensures the best welfare for their pet and does not endanger the local ecosystem. Pet’s (companion animals) must never be released into the wild. It is illegal and for most species this will lead to an untimely and possibly lingering death, as they are not native to this country. Any animals or plants that do survive might become harmful to the environment. If you can no longer keep your pet then seek advice at a local pet store, rescue centre or specialist pet club.
Soiled substrate, cage décor and waste water, particularly from fish tanks or amphibian housing, should also be carefully disposed of or treated so that potentially harmful diseases or live food can’t escape into the wild.
Are you ready?
Now that you have made your way through the presentation, it’s time to take the test and move one step closer to proving your knowledge and receiving your certificate.
But first…
In order to access a Pet Know How test, you first need to register some details.
Why do you need to register?
We collect limited personal data in order to personalise Pet Know How certificates, confirm participation of a Pet Know How test, record your certificate number and personalise your website experience. We do not share data with any third parties or use it for marketing. Please see our privacy policy for full details.
