December 2025 – Tetra

The right fish food

The huge range of food products available makes it far from easy to choose the right fish food. For example, fish food comes in the form of flakes, granules, pellets, sticks and even as live or frozen food. What’s more, each food contains a different composition of vitamins and nutrients, which the fish need different concentrations of. You should therefore not hesitate to invest a little time in finding the right fish food. Choosing the right food is critical to your underwater inhabitants leading a contented life. After all, it helps to keep the fish healthy and improve their well-being. As all the inhabitants of your aquarium have different requirements when it comes to food, it is important to understand their needs. The different dietary groups Fish can generally be divided into three dietary groups: carnivores, herbivores and omnivores. Carnivores (meat eaters) rely on a protein-rich diet. This can be given to them in the form of live or frozen food. They also like dry food in the form of flakes or tablets. Examples of carnivores include fighting fish and several bass species. Herbivores (plant eaters) primarily require plant proteins in their diet. Examples of fish that are largely herbivorous include black mollies and several catfish species. Dry food and tablets should therefore be plant based for these fish. Fast-sinking products like food tablets are particularly suitable for catfish. They can also be given vegetables. However, there are no such things as exclusively herbivorous ornamental fish, so all food should also contain a certain amount of animal protein. Omnivores (meat and plant eaters) make up the largest of the three groups. These primarily include goldfish, gouramis, guppies and swordtails. These fish like both plant and meat-based flake food and are therefore very flexible about what they will eat. Varied feeding As a general rule of thumb, you should give your fish a varied diet so as to eliminate the risk of malnutrition. The fish food should also be balanced and of high quality. One especially good way of achieving variety is through live food such as bloodworms or water fleas. In the summer in particular, these can be easily stored in a water butt. In the winter, frozen food is a particularly good option, especially red bloodworms or water fleas. You should also ensure that food is varied in terms of its ability to sink. For bottom-dwelling fish and, in particular, catfish, you should primarily opt for fast-sinking fish food to prevent the other aquarium inhabitants from eating it while it is sinking. You should also administer slow-sinking food though as some fish species only swim near the surface and accordingly only eat in this tank region. Mouth-appropriate fish food Fish food also has to be appropriate for the fish’s mouths. Fish have different sized mouths, which the food must be suitable for. For example, granulated food is an excellent choice for small fish. The shape of the mouth also affects the way food is eaten. For instance, fish with a superior mouth primarily feed at the surface, fish with an inferior mouth are usually bottom feeders and fish with a terminal mouth are generally mid-water feeders, i.e. they eat in the middle of the aquarium. Different food types for different genera In addition to different types of complete food, which are suitable for all ornamental fish, there are naturally also complete food products that are specially designed for individual fish species. For example, the broadest range of complete food products like mixed flakes are ideal for guppies and many live-bearing fish as omnivores. Several types of complete food in the form of flakes, pellets, sticks or granules are also suitable for cichlids. As described above, catfish primarily require fast-sinking food tablets. Special micro food is available for particularly small fish with a small mouth. There are also special types of complete food for providing species-appropriate nutrition to crustaceans and shrimps, which can be kept in an aquarium of their own. There are also species that require a specialist diet, such as pufferfish, which primarily need snails when living an aquarium. These are not only nutritious for the pufferfish, but also wear down their teeth, which would otherwise get ever bigger as they constantly grow. Frequency of feeding We recommend feeding your underwater friends once or twice a day. Do not give them too much; only as much as they can eat in a few minutes. Excessive amounts of leftover food can cause the water quality to deteriorate. You can be economical with the amount of food you give your fish – it won’t do them any harm to have the occasional diet day. As such, you can even go away for a weekend without worrying about your fish; they can easily survive for a few days without food. There are also special food products for weekends or slightly longer holidays. The fish can eat these as required; they do not instantly dissolve in the water. In summary therefore, when feeding your fish you should opt for a species-appropriate diet that takes into account whether the fish are carnivores, herbivores or omnivores. You should also feed your fish economically, providing them with a varied diet consisting of mouth-appropriate products. If you observe these four summarised points when feeding your fish, you will help them enjoy a healthy and content life.

Blog, WaterCare

Aquascaping

What is aquascaping? We are all aware of the visual appeal of classic aquariums filled with fish, but planted aquariums containing snails or shrimps can also be truly eye-catching – providing they are suitably designed. The design or replication of aesthetic landscapes under water is known as aquascaping. This is an increasingly popular trend in the world of fishkeeping, so much so that there are now plenty of fiercely contended aquascaping contests. This special type of aquarium design can be traced back to Japanese nature photographer and aquarium designer Takashi Amano, who has decisively shaped the concept of aquascaping with his impressive natural aquariums. The difference between classic fishkeeping and aquascaping lies in the structured design or ‘layouts’ of the aquariums. Nature as a source of inspiration Aquascaping is all about creating visually appealing aquariums. The natural world above the water provides inspiration for the aquascaping layouts below it. Aquascapers often try to replicate certain images or scenes from nature, such as forests, mountain ranges or hills. These landscapes are primarily constructed using real plants, stones, roots and caves. As a result, aquascaping is often also referred to as underwater gardening. Aquascaping can involve several types of aquariums, from those containing plants alone to those stocked with snails or even small fish. Creating an aquascape Before aquascapers start setting up an aquarium, they first develop a precise design concept. Only then does the actual implementation begin. First, the appropriate or desired substrate must be added to the aquarium. A substrate slope can be used to create a sense of depth that visually enhances the aquarium. Attention can next be turned to the question of how to divide up the aquarium. This is usually based on the principle of the ‘golden ratio’, a division ratio that determines how the aquarium can best be divided up to achieve a visually harmonious structure. A classic choice is for the sky to make up a third of the overall picture. In addition to the way the aquarium is divided up, the hardscapes are also of key importance. These are the hard landscape materials, such as the right stones and roots. Ideally, only one type of rock and one type of wood should be used. A further aquascaping rule is that using an odd number of stones creates greater visual appeal. If adding roots, it is essential to ensure that they are saturated beforehand as they can otherwise become buoyant when the aquarium is filled with water. Once the hardscapes have been added, it is time for the softscapes, meaning the various plants. A broad range of plants from stem plants to mosses and ferns can be used to create the desired landscape or artwork. There are also designs that incorporate a maximum of three – or even only one – plant species. Softscapes or plants are also used to conceal the technology needed for the aquarium to thrive so as not to detract from the design. On the whole, aquascaping should create a harmonious yet dynamic picture. Aquascaping versus classic fishkeeping In classic aquarium set-ups, little attention is paid to the hardscape elements. Aquatic plants are largely used to positively impact the water quality and provide the fish with safe havens in which they can hide. With aquascaping, precisely the opposite is true. Here, the main focus is on the stones and roots, which should draw the eye. This shows the sheer versatility of the world of fishkeeping, which allows people to give their creativity free rein when designing aquariums.

Blog, FishKnowledge

Keeping fish as pets

The time comes when every child wants a pet of their own. After all, children love animals. But not all animals are suitable for all families. For example, you might rent an apartment where you are prohibited from having popular pets like cats or dogs, or you may have a family member who is allergic to animal hair. Fortunately though, there are other animals that can fulfil your child’s desire for a pet. In fact, fish are becoming an increasingly popular choice as a pet. They are among the oldest vertebrate animals in the world and offer lots of advantages. The advantages of fish Fish make ideal pets for children as they offer a way for them to discover the underwater world and an entire ecosystem. The fish and their behaviour under water can be optimally observed in an aquarium at home. For instance, it is great fun to watch the fish being fed and see how excited they are to eat. Children can also learn a great deal about the various fish and their needs, such as the right water parameters and their importance. When setting up an aquarium both you and your child can give free reign to your imagination. There are all sorts of options for adding your own special touches when designing an underwater world in an aquarium. For example, you can choose the colour of the gravel, different aquatic plants and whichever stones or sculptures take your fancy. A sunken pirate ship can make aquariums an exciting place for both your child and the fish. Researchers from the National Marine Aquarium in Plymouth have also shown that looking into an aquarium and watching fish can reduce stress, promote both well-being and improve concentration skills. Aquariums can particularly help extremely active children to be somewhat calmer. In addition to the above, fish are far easier to care for than many other pets, making them ideal for beginners. Of course, it is important to keep the fish in a species-appropriate manner to give them a long and happy life. Your child therefore learns about consideration and to develop a sense of responsibility at an early age. Choosing the right aquarium Before purchasing any fish, you should first find out about their precise needs. It generally helps to obtain a basic understanding of fishkeeping in advance so you know what to look for in an aquarium. This is because the aquarium, plants and fish must all go well together. It is therefore important to consider which fish you would like to keep and select an aquarium of an appropriate size. Starter sets can be used to make things easier for newcomers to the world of fishkeeping. These usually include an aquarium together with a pump, filter materials and some food. You should ideally try to replicate the natural habitat of the fish by setting up the aquarium with suitable substrate and plants. Plants are particularly important when keeping fish as they supply oxygen and, to a certain extent, can remove any toxic substances from the water. As mentioned above, you can then give free reign to your imagination with regard to how you decorate your aquarium with stones, roots or sculptures. Choose other species carefully Fish come in all sorts of different shapes and colours, making them particularly fascinating. When adding fish to an aquarium, you must naturally also ensure that all of the species in it are compatible. Not all species of fish get on with each other. When choosing fish, you should therefore ideally go for ones that live in different tank regions. This means that they will largely keep out of each other’s way and can live together peacefully. Otherwise the fish may stress each other out. When mixing fish, you should therefore not only check that the species get on with each other but that they also have the same requirements in terms of habitat. Species like goldfish, guppies, barbs, mollies and rainbow fish are particularly ideal for beginners. Even fish need care As mentioned above, fish are much easier to care for than other pets. Despite this, they still require a certain amount of care and attention once you have set up the aquarium and added the fish. For example, as with all pets, you need to feed them daily. It is also necessary to regularly check the water parameters, such as the pH-value, to quickly detect any deterioration in water quality. As fish are in direct contact with the water via their gills, good water quality is essential. You should therefore perform regular partial water changes to provide a suitable level of hygiene. Food residues and any dead plant matter should also be removed from the water. By following these simple measures, you will enable your finned friends to enjoy a long and happy life in your home.

Blog, WaterCare

Aquariums as design elements

Decorate your home with an aquarium Home aquariums are real eye-catchers and look particularly good in living rooms. More than just a habitat for fish and other underwater creatures, an attractive aquarium tailored to the look of your living room will enhance your interiors and turn visitors’ heads. They also exude a feeling of calm, creating an inviting, cosy atmosphere. There are many ways to design an aquarium and make it a beloved, high-quality and modern addition to your home. Benefits of living room aquariums As mentioned above, there are many ways to set up an aquarium and incorporate it into your home. Let your creativity run free – whether you focus on the shape of the aquarium, the plants, the lighting, the rocks or the sculptures, this is your chance to express your personal style. Setting up an aquarium can be a truly joyful experience. Aquariums are a fascinating sight, and will help improve your concentration and encourage you to relax after a stressful day. They also have a calming effect. A well-maintained, functioning aquarium will brighten up any room and add that extra special touch. Designing your aquarium While you are of course free to design and set up your aquarium however you wish, there are two general styles to choose from: a more artistic look, or a natural look. The natural look strives to recreate the habitat of the aquatic creatures as closely as possible. If you choose this option, you will use light or dark gravel and real plants, plus wood and rocks to achieve the look you want. Artistic aquarium designs are very colourful. Depending on your taste, you can use gravel in colours such as orange or blue. Artificial plants are usually used here, also in a variety of colours. You can also add striking sculptures, an underwater castle or a sunken pirate ship. You can even play with the lighting, adding LEDs with colour effects and contrasts. A suitable cabinet in a modern design is the perfect place to store your technical equipment. However, you need to make sure that your cabinet is sturdy, won’t topple over and can bear the weight of the aquarium. Naturally, the fish that will live in your aquarium play an important role in its design. You can populate your community aquarium with large or small fish, single-coloured or multi-coloured fish and keep them in groups, pairs or alone, depending on their social behaviour and requirements. The one thing you must not forget when setting up and decorating your aquarium is that this is a home for your fish, and their needs come first. Finding the right spot for a modern aquarium When incorporating an aquarium into your home, it is crucial to pick a location that will help it stand out. Depending on how much space you have and the size of your aquarium, you can let it stand freely, use it to divide up the room or integrate it into the walls and furniture. Aquariums come in round, square and rectangular designs and various litre sizes to help you make the best use of the space available and match your personal style. Perhaps the most traditional variant is a square aquarium installed on a living room wall. With the right effects, such as an interesting rock formation or an underwater castle, even this classic choice can look great and add an eye-catching feature to your home. If you have a dedicated corner for reading or relaxing, a small aquarium can boost the calming effect and allow your thoughts to drift as you watch the creatures swim around. Naturally, a free-standing aquarium will attract even more attention. You will then be able to look at it from all sides and enjoy an even better view of the fish and other creatures. Alternatively, you can use your aquarium to separate your living space. This can be an elegant way to divide an open living space into an eating area/kitchen and living room. This option is becoming increasingly popular in modern interior design. Even if you don’t want a free-standing aquarium or don’t have enough space, there are many ways to make the aquarium part of the room. Built-in aquariums are a very stylish option: you can have your aquarium installed on a living room wall or book shelf or flush-mounted into the wall. This last option creates a modern and impressive look, particularly if the aquarium is visible from two rooms. With many different design options, aquariums are becoming an increasingly popular feature in modern interiors.

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Keeping Your Tank Clean

An aquarium if left alone can soon become a rather mucky place! The solid wastes released from the fish will accumulate in the gravel and the filter, live plants can shed leaves which will decay in the water and of course the dreaded algae can start to grow coating glass, rock and other surfaces. Keeping the tank clean is not just about aesthetics however, it really is vital for the health of your fishes, invertebrates and plants. Accumulating organic matter, (fish faeces, plant debris etc), will slowly decay in the water. This decay can deprive the precious filter bacteria of oxygen, as well as depriving the fish and invertebrates in the tank of oxygen too. This decaying organic matter can also encourage the growth of opportunistic fish pathogens, not the sort of organisms we want in the tank. Ultimately the decay of this waste will liberate nitrates and phosphates into the water which are likely to encourage blooms of algae. So we can see, as fishkeepers we are strongly incentivised to keep the tank clean! It is tempting to rely on a good filter to keep the tank clean. If all the solid waste gets trapped in the filter sponges then surely the tank is clean? This is not the case as this organic waste is still decaying in the tank water! It is just not visible in the tank. All the problems outlined above will still arise, plus the heavy loading of organic matter in the filter can lead to the delicate ammonia and nitrite oxidising bacteria being displaced from the filter by more competitive ‘heterotrophic’ bacteria. Cleaning planted tanks require care not to disturb the plant’s roots Thus keeping your filter clean is vital, traditional wisdom tells us to clean the sponges in the filter in a bucket filled with tankwater once every week or so – depending on the number and type of fish and the feeding rate in the tank. Small filter sponges, such as those in a Tetra IN Plus range must be cleaned in this way – never clean the sponges in tapwater as those precious ammonia and nitrite oxidising bacteria will be killed off by the chlorine in the tapwater. This will leave your fish tank without a biological filter which is incredibly dangerous for your fishes and invertebrates. Larger canister filters such as the TetraTec EXplus range have distinct sponge and biological stages. Hence really messy sponges could be cleaned in tapwater, but none must be allowed anywhere near the biological filter stage. If in any doubt, simply clean your sponges in a bucket of aquarium water. Another part of the tank where solid wastes will accumulate is the substrate. Basic gravel substrates can be cleaned with a gravel siphon such as a TetraTec GC. These siphon water out of the tank, lifting particles of solid waste with them. The flow can be regulated with a tap to ensure it is of the correct rate to lift solid wastes but not the gravel itself. Planting substrates can be more difficult to clean as we do not want to disturb plant roots and the layering of iron-rich substrate. Use of a length of 5mm diameter airline hose to remove visible solid waste from the substrate surface is the best method. With a clean substrate and filter, the next area to focus on is the glass. Algae magnets such as a TetraTec MC M allow you to clean the glass without getting your hands wet. More stubborn growths of green spot algae can be removed with a mounted blade cleaner such as a TetraTec GS. Just be careful not to scratch the glass or damage the silicone sealant at the corners of the tank. Finally tank glass and aquarium ornaments can be cleaned safely and effectively with TetraTec Easywipes. In summary, keeping your tank clean is not just about looks! It is vital for the long term health and good water quality in your tank – happy cleaning folks!

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How to setup an aquarium

These fish are suitable for your aquarium For beginners, we recommend to either use the heated aquarium for tropical ornamental fish or the unheated goldfish aquarium. Ask your local pet store which fish are compatible with each other so your new community can harmoniously coexist. Our suggestion: In order to enjoy the exciting life in your aquarium water to a maximum, all water layers should be inhabited. Your local pet shop owner knows plenty about which fish swim on the water surface, which fish make use of the entire basin, and whether it is advisable to keep some dwarf shrimp for movement at the bottom of your aquarium. Also ask for the right aquarium technology: while goldfish live in cold water, Guppies and similar types of fish need warmer temperatures and thus an aquarium heater. Make an attractive habitat Plants, roots and other decoration make your aquarium into a beautiful eye-catcher and at the same time fulfill vital functions in your habitat. Aquatic plants produce oxygen and provide your aquarium fish with hiding places. The correct substrate provides the plant’s roots with grip. Decoration elements, such as tree roots, rocks, or even posters for the aquarium background provide visual variety and always bring a new look in your underwater world. The right fish food, that your fish loves With Tetra you find the right food for all aquarium inhabitants. Whether goldfish or Guppies, catfish or dwarf shrimp: with Tetra you feed your fish and shrimp with all vital nutrients and strengthen their immune system thanks to the patented BioActive formula. You also keep the aquarium water clean & clear. Whether it be a classic flake food, nutritious crisp or tasty food tablet, we have the perfect product for each one of your aquarium inhabitants. Easy Water Care Water is life! With proper water care you will enjoy a biologically healthy aquarium that you can maintain with simple measures. Our tips: Use SafeStart when setting up a new aquarium or FilterActive when cleaning the filter. It contains live bacteria that create a biological environment in which your fish can live safe and healthy. Treat your tap water with Tetra AquaSafe to take out Chlorine and Chloramine and create natural aquarium water. Thanks to vitamins, natural biopolymers and trace elements, your fish will thrive in their healthy water! Keep your aquarium water biologically healthy and add Tetra Easy Balance just once a week for ideal long-term maintenance. Check the water quality once a week with the Tetra Test 6in1 test strips.

Blog, WaterCare

Aquariums are good for the soul

Science has now confirmed what fishkeeping fans have known for some time: watching fish, shrimps and so on in their underwater world is relaxing and promotes well-being. Standing by a gently babbling river, watching the water or gazing out over a favourite landscape – again and again, studies confirm that calm moments in nature help people to relax. Researchers at the National Marine Aquarium in Plymouth have now proven that aquariums – and the fish that live in them – offer the same form of relaxation. Its huge tanks have been pulling in the crowds for a long time now. When one of the tanks was restored and gradually filled with new aquatic creatures, the scientists seized the opportunity to conduct a small study. Observing the observers The researchers watched the visitors who looked at the new aquarium and measured various parameters – in particular their blood pressure and pulse to draw conclusions about their stress levels. They also used surveys to ask about the visitors’ health. Participants provided information about their mental well-being. And the results were clear: ‘We were able to show that the underwater landscapes had a positive effect on people’s moods’, explains head researcher Deborah Cracknell. Lots to see Watching the fish in their underwater world had a quantifiable effect on visitors’ stress levels. The longer they spent watching the fish, the greater the impact. To make this clear, the scientists recorded data at three different points: when the aquarium contained only water, when it was half-filled with creatures, and again when the aquarium was completely set up with all fish and plants. They concluded that the more creatures the aquarium contains, the greater the effect. Looking at the aquarium reduced visitors’ heart rates and made them more relaxed. Haven of relaxation Up to now, large aquarium experience centres have seen themselves primarily as places of education and clarification. ‘But they can offer totally different benefits as well’, states Dr Sabine Pahl, co-author of the study. In stressful times, underwater worlds could serve as havens of calm and relaxation – particularly for people who do not have the opportunity to enjoy nature. Watching fish swimming around an aquarium and losing yourself in the experience for long periods reduces stress and helps you stay healthy for longer. And as Cracknell explains, the aquarium does not necessarily have to be huge: ‘It has already been shown several times that even small home aquariums have a calming effect on the body and reduce stress.’ Aquariums are a great choice for everyone, not just experienced aquarists. As well as their calming effect, they are easy to maintain and do not take up too much time. But maintenance is important – only a well-kept aquarium will look nice, keep your fish healthy and help you to feel good too. With various aquatic plants, fish and creatures, an aquarium can be an eye-catching feature in any home and good for the soul – both for you and your guests.

Blog, FishKnowledge

What is fish health?

Defining the concept of ‘health’ can be very tricky, generally, animals are considered ‘healthy’ if they are free from disease, however, disease is itself defined as a state of ill health! These circular definitions can lead to confusion so perhaps a closer look at the causes of ill health in fish may help to hone any definition of health Causes of disease in fish can be categorised into 5 major groups, firstly, environmental causes; what fishkeepers would call ‘water quality’ problems. All fish have environmental requirements, they have a water temperature, pH and hardness range they prefer, and differing tolerances for various natural and exotic pollutants. If the environmental requirements are not met or pollution tolerances are exceeded, then disease occurs. The second type of disease is due to pathogens, infectious agents that can spread from fish to fish. Some are obligate pathogens that can only survive if there are susceptible fish around to infect, others are opportunistic, feeding happily on organic material in the water but switching to a pathogenic phase if the fish become susceptible. The link between environment and pathogen here is very intimate, fish that are weakened by adverse environmental conditions will become much more susceptible to these pathogens. Thus the aquarist who is battling ammonia and nitrite levels in his fish tank will soon encounter pathogenic disease such as the dreaded white spot parasite, Ichtyopthirius multifilis. Diseases of environmental origin are without doubt the most commonly encountered by aquatic professionals and hobbyists alike. Pathogenic disease often arises as a consequence; other causes of disease can be much more esoteric and less regularly encountered. An awareness is still vital to anyone with an interest in fish health and welfare. Many diseases can have their root in malnutrition, fish can be fed incorrect levels of proteins, fats or carbohydrates, but more commonly it is an imbalance of micronutrients such as vitamins and minerals that lie at the heart of the problem. The most commonly cited example is a deficiency of ascorbic acid – vitamin C, this antioxidant agent is vital for many biological functions not least collagen manufacture and many elements of immune system function. Fish show repeatable symptoms of deficiency if not enough is provided in the diet. Ensuring enough of this vitamin reaches the fish is complicated by the water soluble nature of the vitamin and its inherent instability in dry fish foods. Food manufacturers therefore add stabilised forms of vitamin at elevated levels to ensure the required amount reaches the fish. Avoiding food past it’s sell by date is a reliable way to avoid vitamin C deficiency in fish. Disease can also have its root at the genetic level; genes are sequences of the genetic material that code for specific proteins, these then form the builders and building blocks of the fish. Just as typographical errors can be made in a sentence, errors in the sequence of base chemicals in the genetic code lead to mistakes in the protein produced. These mutations are often harmless causing no visible or physiological effect in the fish; occasionally the error has a consequence. This can lead to disease in should this alteration of essential protein structure mean it is no longer be able to perform its role in the complex body system of the fish. We should also remember though that it is this mutation that gives us the infinite variety of life. As more research into fish behaviour and welfare is conducted, it is becoming more apparent that the psychological well being of the fish is just as crucial as good water quality, diet, genetics and the absence of pathogens. Aquarists have known for years that behaviour is a key player in fish health, fish stressed by aggressive attention from a socially dominant tankmate or breeding partner soon succumb to infectious disease. Even too much attention from humans (banging on the glass!), can weaken timid fish. However psychological well being extends much further than the fish not being bullied or scared. ‘Environmental enrichment’ is a hot topic among many animal husbandry professionals; this can be defined as the provision of environmental stimuli to encourage physical and mental activity. Examples of environmental enrichment in the ornamental fish world include target training Archer fish (Toxotes jaculatrix) or puzzle solving for a food reward in Common Octopus (Octopus vulgaris), more recently a goldfish training kit has become available to buy on the internet! At a much more simple level the provision of décor to offer cover, gravel or sand for benthic species, flow for riverine species or the correct spawning substrate would also be considered environmental enrichment, because these make the habitat more conducive to allowing the fish complete its natural behavioural repertoire. It is only through cutting edge welfare research involving monitoring stress markers such as catecholamine and corticosteroid hormones and endogenous opiods (natural pain relief chemicals), that the importance of the fish’s psychological well being will become apparent. So let’s return to our original definition of ‘health’ as an absence of disease. Disease symptoms are caused when the fish’s environmental requirements are not met, when pathogens infect, when the diet is incorrect, from a genetic origin or when the fish’s psychological needs are not met. Thus when appraising the health of our fish we must consider all of these factors.

Blog, FishKnowledge

Spotting ill health in your fish

In order to recognise a poorly fish, we must first know what a fish looks like and how it behaves when healthy. We can only recognise the ‘abnormal’ when we know what is normal. For example, a goldfish keeper may become concerned about the presence of small white spots on the gill covers and pectoral fins of their fish. Further investigation will lead them to discover that these small white spots are not a sign of disease but are actually special spawning pimples that cover certain parts of male goldfish at spawning time. A tropical fishkeeper could become concerned that their Synodontis catfish are swimming upside down – this could be a sign of a swim bladder disorder. Again further investigation will lead the fishkeeper to discover that the fish are actually ‘upside-down catfish’, which swim happily in an inverted position when juvenile, often resorting to a more conventional posture as adult fish. These two examples highlight the need to know your fish! Know your fish starts before you have even purchased them from your aquatic store. When you read up on the potential size, feeding and water quality requirements of any potential new fish, try to also seek information about the natural appearance of the fish at different stages of their life cycle and their natural ‘normal’ behaviour. Kribensis cichlids (Pelvicachromis pulcher) for example show a markedly red belly at spawning time, this could be mistaken for bacterial erythrema. Clown loaches (Chromobotia macracanthus), are notorious for the eccentric behaviours. Youtube has a wealth of videos of healthy aquarium and pond fish, so these days we can see not only normal appearance but normal behaviour too. Upon acquiring your fish, you should familiarise yourself with the individuals natural appearance and its behaviour. In the first few days in the tank, your new fish are likely to be very timid and may decline feeding, however as they settle most common freshwater aquarium inhabitants will venture out into the tank and respond to feeding. Notice the swimming patterns of your fish, how quickly they eat food and the method of food intake. Feeding time offers an excellent time for a brief visual healthcheck of your fishes. However, as stressed above, we must be familiar with ‘normal’ appearance and behaviour of healthy fish in order to recognise ‘abnormal’ and thus potential ill health. Abnormal signs to look out for can be split into behavioural and morphological deviations from the accepted ‘normal’ state of your fish. Behavioural indicators of ill health include gasping for air at the water surface, a common sign of gill disease or water quality problems in most fishes – in air breathing fishes such as the Lungfish this is perfectly normal behaviour. Changes in the swimming activity are a sure sign of potential ill health. If a normally active fish ceases swimming activity, becoming lethargic and swimming only when disturbed, then this is a strong indicator of ill health. For sedentary carnivorous fishes, this is again a common ‘normal’ behaviour. Fish infected by skin parasites or irritated by certain water pollutants, will flick and scratch against objects in the aquarium or pond. Erratic darting motion instead of smooth swimming is often seen in small tropical aquarium fishes when they are infected by internal parasites or bacteria. These affect the swimbladder and occasionally the neuromuscular systems, which has an affect on posture and locomotory activity. Assuming an abnormal posture, such as a lopsided gait or even fully upside-down, is usually a sign of a swimbladder problem, a common complaint in fancy aquarium goldfish. The same problems can also cause the fish to lose its normal neutral buoyancy, and they either sink or rise when at rest. A fish that normally feeds voraciously, refusing food is a sure sign of ill health. As in all fish health problems, the first thing to check is that the water quality is within the preferred limits of the fish. As can be seen we must carefully observe our fishes when they are healthy in order to recognise behavioural changes shown when they are sick. The same is true for the external appearance of the fish, familiarise yourself with its colours, body contours and finnage. External signs of disease are all some deviation from the normal condition. If a fish’s skin is irritated either by pollutant in the water such as ammonia, or by infection with a skin parasite, the first response the fish will show, (In addition to the flicking and scratching mentioned above), is overproduction of mucous. The mucous layer is highly protective and the fish increases its production when the skin is irritated. This overproduction of skin mucous makes the fish’s colours look duller and it assumes a grey hazy appearance. Most external parasite infections cause generalised symptoms, one however, known as white spot, causes a very recognisable condition. As the name suggests, infection of the skin with the white spot parasite causes the fish to develop tiny white pimples over its body. The white spots are around 1mm in diameter, they tend to develop on the fins first before progressing over the body as the infection proceeds. Scaleless fishes such as Clown Loach are highly susceptible. Another very recognisable condition is finrot, although there are many possible causes. The fins of a healthy fish should be complete, symmetrical and of a uniform consistency. During finrot the skin between the bony fin rays rots away leaving the fish with decaying tissue where the fins used to be. If the cause of the finrot is identified and treated, the fins rapidly grow back. Finrot is caused either by water pollution, most commonly extremes of pH or ammonia poisoning. Infection with certain types of bacteria can also cause the problem. The delicate tissue of the mouth is also prone to a similar necrosis. Bacterial infection can also cause large open sores on the skin of the fish called ulcers. These are very damaging and must be treated early. Many internal problems can manifest themselves with external