Tetras and Pencilfish
Some of the most recognisable aquarium fish, tetras and pencilfish can make excellent pets on account of their peaceful shoaling nature. The neon tetra may be the most iconic tropical aquarium fish, but there are many other tetras and pencilfish available with sizes ranging from 2-10cm. Discover the wonderful world of tetras and pencilfish and learn how to create their perfect habitat.
What next?
View the information below to learn the essentials for owning tetras and pencilfish.
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 owning tetras and pencilfish
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 owning tetras and pencilfish.
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 tetras and pencilfish knowledge.
Introduction
Tetras are some of the most recognisable aquarium fish. They are from the family Characidae and originally occur in South America and Africa, although the majority of those in the aquarium trade are now captive bred. Pencilfish are less well-known and are from the family Lebiasinidae. They also occur mainly in South America, with much fewer species being captive bred for the aquarium trade. Both tetras and pencilfish are generally small, colourful and peaceful fish, however, there are some exceptions. Most tetras and pencilfish are undemanding aquarium inhabitants and are easy to keep.
Biology
Tetras grow to a range of sizes, but most stay between 2-5cm, with some larger species reaching nearer 10cm.
There are fewer species of pencilfish, and even fewer in the trade, but they generally stay smaller and don’t often grow above 5cm.
Although small, these fish can live several years in a well matured set-up with good water quality.
Tetras and pencilfish are shoaling fish and should be kept in groups of at least five in the home aquarium, but more is better. Tetras or pencilfish kept singly or in too small groups will often become stressed.
It is difficult to sex most species of fish unless they are breeding, but in some species such as the Congo tetra the males are more colourful and have longer fins than the females. Similarly, spawning male pencilfish will become a lot brighter in colour.
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. Signs of disease can include clamped fins, flicking against gravel or décor and shimmying (shaking). Diseases can be easily carried by fish that do not show any clinical signs. If in doubt, ask your OATA retailer for advice as they will have in-depth knowledge and experience.
Water requirements
Captive bred tetras and pencilfish are usually undemanding of water chemistry and their suggested parameters are shown below. These parameters are a general guide for these groups of fish, so it is important to check with your OATA retailer for any species-specific requirements before purchasing.
Temperature: between 22-27°C
pH: 6.5-8.0
Ammonia: Zero mg per litre
Nitrite: Zero mg per litre
Nitrate: Not to exceed 20 mg per litre above normal tap water levels
General hardness: Soft-medium (4-12°dH)
Carbonate hardness: Soft-medium (3-10°dkH)
If your tetras or pencilfish are wild caught, ask your OATA retailer for advice on what parameters they recommend.
Aquarium requirements
As a general rule you should, within reason, buy an aquarium as large as possible. Ideally, it should be able to accommodate at least a small shoal of tetras or pencilfish. It is recommended that an aquarium of at least 45 litres for a small shoal of a smaller species and at least an 80 litre aquarium for the larger species (5cm+). The larger the aquarium, the more stable the environmental conditions such as temperature and water quality will be. Whatever the size, a filter is always essential.
Aquarium requirements continued
The tank should also have aquarium gravel or sand and ideally live plants present to provide cover. If live plants are not used, then the addition of plastic plants and suitable ornaments is recommended, such as plant pots or model caves, which supplies the fish with shelter. It is also important to provide tetras and pencilfish with space to swim, and a gentle current for the smaller species.
A heater is required to maintain a suitable temperature all year round. To minimise fluctuations in water temperature, the aquarium should not be situated near any draughts or heat sources. It should also be out of direct sunlight and away from loud noises, vibrations and sudden movements. Overhead tank lighting is recommended to maintain correct day-night cycle.
Checking your aquarium
Before adding any fish, seek advice from your OATA retailer to make sure that your aquarium is an appropriate size for the number of tetras or pencilfish you would like to keep. Check that the water quality in your aquarium is suitable i.e. levels of ammonia and nitrite are zero. 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 from the fish, leading to unhealthy levels of ammonia and nitrite, which may cause fish to become ill or die.
Introducing your fish
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 because fish are easily stressed by bright lights, extreme temperatures, noise and movement.
Once home, your fish will need to acclimatise to their new environment and a common method of doing this is known as the ‘floating bag’ method. Switch off the aquarium lights and take the bag containing your new fish out of its outer wrappings carefully, avoiding exposure to bright light. Float the bag in the water of your tank to ensure the temperature in the bag is the same as the aquarium water. After 10 minutes, slowly introduce small amounts of aquarium water into the bag containing the fish for up to 20 minutes. Once complete, carefully release the fish into the aquarium whilst introducing as little bag water into the aquarium as possible. After this, 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 doubt, contact your OATA retailer for advice.
Maintenance
Maintain the water in the aquarium within the accepted parameters highlighted in this guide. You may need to do regular water changes to achieve this.
Always buy test kits and regularly check the water for ammonia, nitrite, nitrate and pH. This will allow you to make sure the water in your aquarium is not causing welfare problems for your tetras or pencilfish. Establish a routine for testing the water in your aquarium. Record your results to enable you to identify fluctuations quickly and also check the temperature of the water.
Never siphon by mouth a fish tank can harbour bacteria which can be harmful if swallowed. Buy a specially designed aquarium gravel cleaner which can be started or primed without the need to place the siphon in your mouth. Always wash your hands making sure to rinse off all soap residues, before putting them into your aquarium, or use long sleeved rubber gloves. Wash your hands again afterwards and certainly before eating, drinking or smoking.
Maintenance continued
Water testing kits are essential so that water quality can be checked on a regular basis (once a week) to ensure it does not slip below the standards given in this guide.
At least once every week, a partial water change of 25% is strongly recommended (a siphon device is useful to remove solid waste from the gravel). The water should be tested regularly (at least once per week) to ensure that ammonia and nitrites don’t build up. Ensure that the replacement water is treated with tap water conditioner to remove any harmful chlorine or chloramine present before adding to the aquarium.
Filters should be checked for blockages. If the filter needs cleaning, do not run it under the tap because any chlorine or chloramine present may kill the beneficial bacterial population that has established in the media. Instead, it should be rinsed lightly in the tank water which is removed during a partial water change as this reduces the amount of bacteria which are lost.
Good husbandry is essential as tetras and pencilfish can be stressed by even the smallest amounts of ammonia and nitrite which may then cause them to develop various diseases. Test the water to monitor the ammonia, nitrite and nitrate levels, together with pH and water hardness every week, especially during initial set-up and after adding extra fish.
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.
Feeding
Both tetras and pencilfish are omnivorous and will take most food types. In the home aquarium, they should be fed with a good quality flake or granule. They will also benefit from being fed small items of live or frozen food such as daphnia, small bloodworm or tubifex.
Tetras and pencilfish should only be fed what they can eat within a few minutes once a day. Take care not to overfeed as this can lead to a build-up of uneaten food which breaks down releasing toxic waste into the water. If in doubt, ask your OATA retailer for advice on appropriate feeding levels.
Compatibility
The smaller species such as neon tetras or Beckford’s pencilfish should not be kept with any fish large enough to eat them. The larger or more boisterous species such as Buenos Aires tetra should not be kept with any timid or long finned fish as they may nip their fins. Tetras and pencilfish mix best with species of a similar size and temperament to themselves.
Breeding
Tetras and pencilfish can be bred in the home aquarium, although it is unlikely to be very successful, particularly in a community aquarium. Spawning can be induced by feeding lots of frozen or live food and decreasing the temperature to mimic the rainy season. Both are egg scatterers and will scatter eggs over plants, leaf litter and in the substrate. Any eggs that aren’t eaten by the aquarium inhabitants will hatch within a couple of days and after a couple more days, small fry should be seen. For best results, a dedicated set-up and specialist fry foods are required.
Before purchasing your tetras and pencilfish
Before purchase make sure:
You have the appropriate equipment and position for the aquarium
You have researched all the species in which you are interested and your final choices are all compatible
You are familiar with how to transport and release your fish
You are aware of the daily, weekly and monthly maintenance your aquarium will require
You are prepared to look after your fish properly for the duration of their life
The aquarium is of a suitable size that ideally can accommodate the fish once they are fully grown
Water parameters are as advised in this guide
Aquarium is cycled and ready to receive fish
Shopping list
Owning a pet is a financial as well as a moral responsibility. In order to properly care for tetras and pencilfish the following items are essential and you should ensure that you are ready to commit to both the one-off and ongoing costs involved with having a pet.
Water testing kits (ideally ammonia, nitrite, nitrate, pH and water hardness)
Gravel cleaner/siphon cleaning device (recommended)
Aquarium decorations and/or live plants
Bucket for water changes
Glass or acrylic aquarium
Filter
Heater
Lighting (required for live plants)
Gravel or sand
Tap water conditioner/dechlorinator
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.
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