FishKnowledge

Characteristics/origin The swordtail gets its name from the shape of its tail fin. The lower part of the fin sticks out like a sword and often measures up to a third of its total body length. However, only the males have this sword-like part on their tail fins. Xiphophorus helleri come from Central America, where they can be found from Mexico to Guatemala. They belong to the live-bearing toothcarp family. Kept correctly, the males can grow to up to 10 cm in length (not counting the sword-like part of the tail fin). The females are a little larger. They can also live to 5 years of age. They were originally brown and green in colour but, thanks to the different breeds and cross-breeds, there are now many different bred species; those with red colourings are particularly popular. Aquarium and water To create an appropriate environment, Xiphophorus helleri should be kept in an aquarium with a minimum volume of 100 litres. Swordtails can be kept in aquarium water at tropical temperatures of 20°C to 27°C. Ideally, the water should be neutral to slightly alkaline (pH value: 7.0 – 8.5) with a hardness level of approx. 10 – 30° dGH. Keeping conditions Swordtails tend to form groups, and should therefore be kept in a shoal with many conspecifics. It is recommended to always keep just one male with several females because male swordtails can be very aggressive toward one another. Given their highly adaptable nature, these fish are suitable for community tanks. However, they should not be mixed with small and very sensitive fish. They work particularly well with robust barbs, other live-bearing toothcarps and bottom-feeding fish like catfish. Swordtails tend to prefer the middle to upper regions of the aquarium. One distinguishing feature of the male Xiphophorus helleri is that there are two types: early-maturing and late-maturing. Late-maturing males develop their sexual characteristics very late and are often mistaken for females at first. Early-maturing males develop their sexualcharacteristics at an early stage. Planting and decoration There should be abundant vegetation around the edges of the aquarium to allow the fish to withdraw and hide. You can also add a few floating plants. However, there must always be enough space for the fish to swim. It is also recommended to put a lid or cover on your aquarium because swordtails are very good jumpers.  Diet Swordtails are omnivores and can be fed dry food, live food and frozen food. TetraMin and Tetra Menu are particularly suitable.

Characteristics/origin The black molly is the black cultivated breed of molly. As its name suggests, it has a black colouring: deep black scales covering its entire body along with a velvety sheen. There are also many colourful varieties with special tail fins. Mollies generally come from Central and South America, and can be found from Mexico to Colombia. Black mollies belong to the live-bearing toothcarp family. If kept correctly, mollies can grow to around 6 – 10 cm in length and live to be 5 years old. The males have larger dorsal fins than the females, making it easy to tell them apart. Like all livebearers, the males also have a modified anal fin, the gonopodium.  Aquarium and water To create an appropriate environment, black mollies should be kept in an aquarium with a minimum volume of 100 litres. They can be kept in aquarium water at tropical temperatures of 24°C to 30°C. Ideally, the water should be slightly acidic to slightly alkaline (pH value: 7.2 – 8.2) with a hardness level of approx. 11 – 30° dGH. While very robust, mollies are sensitive to fluctuations in temperature and pH value. They generally do not like softer water and should therefore be kept in harder water. Keeping conditions Black mollies are not actually shoaling fish, but feel most comfortable in groups of several creatures. There should always be more females than males in the aquarium. These very peaceful fish are well-suited to community tanks and mix particularly well with catfish, guppies and platies. Black mollies tend to prefer the middle to upper regions of the aquarium. Lyretail Molly black fish, freshwater aquarium fish; Shutterstock ID 1372347428; Kostenstelle / Nummer: 55110; Projekt (Nummer): Janine BERDELMANN Planting and decoration Black mollies feel most comfortable in water with abundant vegetation. There should be plenty of vegetation at the edges of the aquarium in particular to provide good places for the mollies to withdraw and hide. This ensures that the creatures in the rest of the aquarium still have plenty of room to swim. Fast-growing plants that reach the surface of the water are recommended in particular. Diet Black mollies are generally herbivorous. They should be fed mainly with fine plant-based flake food like Tetra Phyll Flakes. For a treat and extra variety, they can also be given Tetra Delica Bloodworms. They are also known to eat algae.

The harlequin rasbora at a glance: Fish size 4 to 5 cm Tank size From 54 l Temperature 22°C – 26°C pH level 5.0 – 7.0 Compatible with Labyrinth fish, loaches, other danios Tank region Middle Food Eats all smaller food types, particularly likes black bloodworms The harlequin rasbora belongs to the carp family (cyprinidae), and within this to the danios (danionidae). Its scientific name is trigonostigma heteromorpha (until 1999 it was known as rasbora heteromorpha). “Heteromorpha” comes from the fact that its shape differs slightly from that of other danios, with a deeper body. The harlequin rasbora is sociable, an active swimmer and one of the most popular aquarium fishes. It originally comes from Malaysia, Indonesia, Sumatra and Thailand, where it can be found in large shoals in black-water swamps and streams. It was discovered in 1904 and the first wild fish were imported to Europe in 1906. It is easily recognisable thanks to the black triangular patch that starts below its dorsal fin and extends to its tail fin. Its silver scales also give off a reddish to copper sheen. The shimmering colours of its relatively large scales earned it the name “harlequin rasbora”. The males tend to be a little slimmer than the females. Their triangular patches also differ. While the patch ends at the root of the tail fin in females, it continues through to the middle of the tail fin in males. Harlequin rasbora: Aquarium and water To create an appropriate habitat, these peaceful shoal fish should be kept in an aquarium of at least 54 litres. In accordance with its natural habitat, the harlequin rasbora feels most at home in black water. The best way to give the water a dark, slightly acidic quality is to filter it over peat or add peat extracts. Wild harlequin rasboras live in very soft water of below 3 °dH. However, bred harlequin rasboras now cope very well in neutral or even slightly hard water. Harlequin rasbora: Keeping conditions In the wild, harlequin rasboras form loose social groups – to ensure that they feel safe and show their entire range of behaviour, they must be kept in groups of at least eight to ten fish. The group also brings out the colour of their dark triangular patch against its silvery background. If the fish are happy, they can live for up to six years. Their peaceful nature means that harlequin rasboras can be easily kept with other fish; the best options include labyrinth fish, loaches and other danios. Harlequin rasbora: Planting and decoration Trigonostigma heteromorpha likes a dark aquarium with a smattering of vegetation. It needs both places to hide and open spaces to swim. Its colours look best in muted light (achieved, for example, with a covering of floating plants) with a dark substrate. If you wish to breed these freshwater fish, you will need to take their reproduction strategy into account when choosing plants: they generally lay their eggs on the underside of broadleaf plants. Suitable plants include cryptocoryne and swampweeds (hygrophila). If planning to breed fish, you will also need to think about water hardness, which must be very low. The pH level must be slightly acidic. Therefore, these are not easy fish for beginners to breed. Harlequin rasbora: Diet These fish will eat almost any form of dry food. You can make them particularly happy by regularly feeding them live food. They particularly like black bloodworms.

Characteristics/origin The individual members of the neon family all have similar colourings, making it tricky to tell them apart. The neon tetra, cardinal tetra fish and blue neon tetra all have a red-blue colour. The different proportions of colours are what make them distinct. In keeping with its name, the blue neon tetra has the largest proportion of blue in its scales and just a small strip of red on its abdominal area. Paracheirodon simulans comes from South America and is mainly found in the Rio Negro in Brazil. Reaching a maximum size of 3.5 cm, the blue neon tetra is the smallest member of the characin family. The females are plumper than the males, but their small size tends to make it difficult to tell the sexes apart. They can live for up to 5 years. Aquarium and water The aquarium should have a volume of at least 60 litres. To create an appropriate habitat, the water temperature should be between 23°C and 27°C; these fish love warmth. The water should be slightly acidic (pH value: approx. 5.5 – 6.5). Neon tetras prefer a water hardness of approx. 3 – 10° dGH. Keeping conditions Blue neon tetras are true shoaling fish and should therefore be kept in a large shoal with an appropriate number of creatures. They are very peaceful fish, making them well-suited to community tanks. However, they should only be mixed with other peaceful, small fish of the same size. This means they mix particularly well with small catfish. Blue neon tetras prefer the middle regions of the aquarium. Planting and decoration Paracheirodon simulans prefer aquariums with dense, delicate plants in which they can hide. Naturally, there should also be plenty of room for the fish to swim. Floating plants and roots can also be added to the aquarium. A dark substrate will set off their blue colouring particularly well. Diet These fish are omnivores, but mainly eat very fine-grained food. Tetra Micro Crisps and Tetra Micro Pellets are particularly suitable. If you wish to give your Paracheirodon simulans a special treat, you can also feed them Tetra Delica Brine Shrimps – a natural food that makes a welcome change.

Colourful bubble nest builders Betta Splendens, commonly known as Siamese fighting fish or just Betta, are an aquarist favourite primarily for their extraordinary range and vibrancy of colour, but also for their fascinating ‘Bubble Nesting’. The male builds a floating nest of saliva bubbles where, should they find a mate, the fertilized eggs will be deposited. Betta Splendens originate from South-East Asia, along with their close cousins, the Betta Imbellis, Betta Mahachaiensis and Betta Smaragdina. All betta are members of the Grourami family (Osphronemidae) and  remarkable for their labyrinth organ, a specialised adaptation to their respiratory system that has a similar function to human lungs and allows them to breathe air directly from the atmosphere; this is in addition to their gills which can take oxygen from water. This adaptation means the Betta can survive in oxygen poor water and gives them a natural advantage over fish relying on just their gills. Betta Splendens variations The Betta Splendens have been selectively bread for hundreds of years, this practice originally was intended to enhance their aggressive traits and engage in the now illegal, fish fighting competitions.  In modern times these fish have been sort after and selectively bred for their aesthetics and to develop a vast variety of colours and fin shapes. The most common are the Veiltail, known for its long veil-like fins, the Halfmoon, recognisable by its 180 degree tail fin and the Dumbo which sports extra-large pectoral fins which look like elephant ears. Keeping Conditions Male Betta Splendens are best kept alone due to their territorial and aggressive nature, only introduce a female should you be interested in the fish breeding. Be aware that Betta often mistake a potential mate for an adversary and quite commonly will attack, which can result in the death of one of the fish. Female Betta are often kept in groups known as Sororities, but it is important to remember that they can be as aggressive as their male counterparts, so a heavily planted tank with many retreats and careful monitoring is essential for their wellbeing. A male Betta building it’s bubble nest Water, Planting and Decoration Betta, unfortunately, have a reputation for being healthy and happy in the tiniest of aquarium due to the misconception that in the wild they live in shallow puddles. Although, their natural habitat does change, outside the dry season Betta enjoy a territory about three feet square and as such any Betta should be kept in as large a tank as possible, but avoiding anything below 40 litres, with a water temperature of at least 24oC. A Betta’s natural habitat is a tangle of plants, and bettas feel much happier in planted aquariums where they can hide and periodically sit on the leaves. Betta spend most of their time at the top of the tank near the surface of the water, as such, the choice of substrate is less important but they really do enjoy floating plants as this can give them an anchor for their bubble nests. Diet Siamese fighting fish are primarily carnivores (meat-eaters). Therefore, they should mainly be fed special foods such as Tetra Betta. These foods contain ingredients that are based on the fishes’ natural diet, and their worm-like shape encourages appropriate feeding. For extra variety, Siamese fighting fish also enjoy natural foods such as Tetra Delica Bloodworms.

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.

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.

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