TAKE IT STEADY
You can not buy an aquarium and set it up with fish all at once, since keeping fish successfuly relies on providing a stable, matured environment. Planning is essential; be prepared to take your time setting up your tank and stoking it slowly over a period of weeks and months.
Why is it worth having an aquarium?
What makes fish one of the most popular pets in the world? You cannot hold fish, stroke or play with it. But we enjoy watching these beautiful animals and the way they behave, we love caring for a self-contained world that relies completely upon us. To keep fish successfully we must understand something about their biology and chemistry. Fish are interesting creatures and with hundreds to choose from, each one has its own character and distinct style of behaviour. These qualities, combined with the relative ease of keeping and low running costs, makes tropical fish the ideal pets for many people. Unlike other popular pets fish live in water and this is what makes their care so different. But keeping fish is much more about maintaining their environment – the aquarium – than the fish themselves. If you provide the right aquarium conditions, maintain the quality of the water and feed them properly, your tropical fish will look after themselves.
The tropical fish trade
Most tropical freshwater aquarium fish are captive-bred, however, some are still caught from the wild, and this is usually done with care rather than destructively. Some common, captive bred aquarium fish are actually extinct in the wild due to the destruction of their habitats, rather than because they are being caught for the aquarium trade and they only continue to exist because of their popularity as pets.
How fish breathe
Fish require oxygen to survive unlike us they get it from water. As water passes over the girls that contain blood vessels, oxygen is absorbed through a thin membrane into fish's blood. The dissolved oxygen comes from the surrounding air and enters at the water surface. More oxygen can enter the water when the surface is agitated by a filter or airpump. As well as oxygen fish can also absorb pollutants and toxins from the water, which is why maintaining good water quality is such an important part of fish keeping.
Cherry Barbs are under threat in the wild, but widely bred in Far Eastern fish farms.
Different shapes and sizes
There are hundreds of aquarium fish to choose from, to be able to choose
the right mixture of species is part of successful fishkeeping. Good dealers
will be able to give you some advice on all the species they sell, but you can also conduct your own research on any fish you intend to buy. Remember that most fish available in pet shops are young and their size and temperament can change significantly as they get older.
Mixing different groups
Tropical aquarium fish can be divided into groups, such as barbs, tetras, gouramis , danios, rainbows, livebearers, cichlids, catfish and loaches. The fish within a group usually share similar requirements and behaviours in the aquarium, but there are always exceptions to the rule. Mixing fish from different groups makes aquarium more interesting to watch, with fish swimming at all levels – surface, midwater and bottom.
Each fin plays a specific role in the movement of the fish, and also helps to balance in the water and fight agianst the water currents. A flick of the caudal fin gives the fish a kick-start and the body flexes from side to side to keep it moving. The anal fin reduced rolling acting like a keel.
What is 'community' fish?
The term 'community' describes different species of fish that lives happily together. However, this term can only be used as a guide as not all community fish will coexist without causing problems.
For example, a fish that is likely to nip at long-fineed species will live perfectly happy in a community of fishes without long fins, therefore can still be considered a community fish. Other quieter natured fish prefer to be kept in a peaceful environment and mixing it with overactive species may cause undue stress. It is a good idea to check the individual needs of the fish you intend to house together
What kind of tank?
There is a vast range of aquarium designs to choose from, such as wall-mounted picture frame tanks, circular aquariums and coffee table-style tanks. The main aspect to consider is whether the aquarium is suitable for the type of fish you intend to keep. Some of the more unusual aquariums are not practical, before purchasing you should consider how easy the aquarium will be to maintain, how much room there is for fish and decor, and whether the tank will be free from vibrations.
Reducing the risk of predation
To avoid predation in the aquarium it is best to choose species that grow to a similar size. Many big fish, especially the larger cichlids, are active predators that hunt down their prey, but virtually all fish will happily eat easy-to-catch species that are small enough to fit in their mouths.
Aggression in the aquarium
For some fish aggression is a natural and healthy part of their lifestyle; for others it can result in bulluing and stress, causing physical damage, disease and even the death of an unlucky victim. There is always squabbling within groups of small fish, but this is simply status reinforcement and rarely causes harm. In some species, such as many livebearers, males can constantly harass females in order to breed. To avoid excessive stress amongst livebearers, either keep only one sex, or keeping twice as many females as males so that that aggression is spread more thinly.
Staking out territories
In the wild, being territorial makes sense; it means securing the best feeding grounds or chasing fish away from a site where young are being guarded.Not all fish are territorial; this trait is normally seen in cichlids, some catfish, loaches and gouramis. Some fish, such as dwarf cichlids, only hold small territories and can normally be kept in a community aquarium without harm; others may be heavily territorial and only suited for larger tanks.
Shoaling is a natural instinct
Most small fish are shoaling species and prefer to be kept in larger groups. In the wild it help them to avoid predators and find food easily. Shoaling fish kept on their own can become stressed and may fall ill. In groups small fish feel more confident, they display brighter colours and become more active.
SQUABBLES ARE GOOD
Some fin-nipping fish such as infamous tiger barb, are much better behaved when kept in large numbers. This is
because the fin-nipping habit is an extension of the fish's natural squabbling nature. If the group is large enough, the fish remain occupied with each other and ignore other fish.
Fish use objects such as rocks and wood to define territories in an aquarium. If the fish is causing trouble because of its territorial behaviour, moving the tank decor around will remove established territories, creating a more even 'balance of power' within the tank.
LINE OF SIHGT
Many territorial fish will only act aggressively towards fish within immediate sight. Creating areas of dense, tall plants and breaking the tank into distinct areas will help fish to stay out of the sight of aggressive individuals.
Safety and access
If you intend to buy a large aquarium, make sure the floor is strong enough to support its weight and only use cabinets specifically designed for large aquariums. There should be an electrical socket nearby and plenty of room around the aquarium to access all the equipment for maintenance. When you place your tank in its final location, make sure it is level before you fill it. If the aquarium does not have a raised base, be sure to place a layer of polystyrene or plastic foam between the glass base and the cabinet. Remember that once the tank is filled, it is extremely heavy and very difficult to move.
Before purchasing an aquarium you should look aroundyour home and find a suitable place for it. Position aquarium away from any sources of heat ( which may cause fluctuation in water temperature) or doorway as sudden movement can stress the fish. Avoid placing the tank near hi-fi equipment, televisions and domestic appliances as vibrations can also upset fish. A direct sunlight may cause algae or heat problems in the summer therefore place an aquarium away from windows in a shady part of the house.
WATER AND ELECTRICITY
Be very careful when using water and electricity. A good safety tip is to make sure that any cables are positioned with a 'drip loop' , where the cable hands below the plug socket so that any water running down the cable does not enter the socket.
BIG IS BEST
A large volume of water is much more stable than a small one. Temperature changes occur more slowly and any pollution is diluted. It is often easier, therefore, to keep a larger tank then a smaller one.
Standard rectangular tank are easy to manufacture and therefore cheaper to buy, while curved glass or many-sided tanks are more expensive. Rectangular tanks are also have a greater viewing area and are usually easier to decorate.
Many stores offer All-in-one solutions, where the aquarium is supplied complete with all the essential equipment required to prepare it for the fish. These usually represent much better value for money than buying the items separately, and eliminate the worry of making sure you choose the right filters, heaters, lights and other equipment.
CHOOSING A TANK
A filter - the most important technical device. It provides the filtration of water in the aquarium, that is its purification of all kinds of impurities. A basic filter draws water through a sponge, which traps waste particles and keeps the water looking clean. In addition, beneficial bacteria grows on the sponge ( or on other filter material in larger filters) and these remove harmful pollutants, make in the water safe for your fish.
Tropical fish require temperature between 23–26°C. To achieve this, use a heater with thermostat, which will switch itself on and off as required to maintain the water temperature. Place the thermostat well below the water surface and at an angle in the tank, where there is sufficient waterflow to enable an even distribution of heat. Make sure that the heating element is not exposed to air during water changes.
An aquarium should be illuminated for 10-12 hours a day, to achieve this, an artificial light source should be used. A single fluorescent tube will be enough for basic viewing, whilst two tubes will produce a stronger light. You can also buy tubes that produce light specifically to promote plant growth or to intensify the fishes colour patterns. Many aquariums are supplied with suitable lighting already built in, but if you are installing your own, make sure you only use the light design for aquariums. Household lighting is likely to produce too much heat and may shatter if accidentally splashed.
Substrates in the aquarium
Substrate has multiple roles in an aquarium: it is the environment for plants' rootslife, it intensifies biological filtration and provides natural decoration of the tank. The thickness of the substratelayer in an aqaurium should be 2-7 cm depending on the look of your tank. After transporting gravel home it has to be washed very thoroughly under running tap water to remove all of the impurities out of it. Avoid any gravel with sharp edges, as these will damage the sensitive barbels of bottom dwelling fish. Plants will do better in a smaller-grain substrate and you can also add natural supplements to the substrate to improve growing conditions.
Buy rocks and wood from aquatic dealers
Natural rocks and wood are available from aquatic dealers and this is the only place you should buy them. Many unsuitable rock types contain dangerous metals or substances that alter water chemistry, and some woods can rot and pollute the aquarium. The best kind of wood for tanks is Bogwood (long-dead tree roots that have been preserved in boggy conditions). It can release tannins that can stain water brown, but this is not harmful. Soaking Bogwood in several changes of clean water before use can help to reduce staining.
There are many backgrounds available for aquariums, ranging from simple sheet of plastic to 3-dimensional, artificial rocks faces. Backgrounds help to create a more natural tank and hide unattractive cables or distracting wallpaper, a simple black black background is often the best choice and will show the fishes' colours well.
LIVE OR ARTIFICIAL PLANTS
Live plants have many benefits over artificial ones: they can provide an additional food source, absorb pollutants, help slow algae growth and create a more natural-looking tank. However, if the tank is home to plant-eating fish or the substrate is unsuitable for live plants, artificial ones will provide an easy and realistic alternative.
ALL ABOUT WATER
Keeping the water clean
Fish excrete waste in the aquarium, which results in the production of ammonia and nitrites, both of which are toxic to fish. A filter will remove ammonia and nitrite by creating a suitable home for bacteria to grow and 'feed' on these toxins, but this can take a little time. The bacteria that settle in your filter only grow as the waste levels in your aquarium increase. This is why it is important to ensure waste levels build up at a slow and steady rate, which can be achieved by stocking your tank with fish slowly, and taking care to avoid overfeeding your fish.
Water testing is an early warning system.
The only way to monitor the levels of ammonia and nitrite is to test the tank water regularly. By keeping a close eye on water conditions, you can take action to avoid serious problems before they occur. Morden test kits are relatively quick and easy to use. In a new tank, test for ammonia and nitrite at least twice a week for the first few weeks. Reduce the feeding levels if either of these pollutants are present.
Different kinds of water.
Depending on where you live, your tapwater will have varying degrees of minerals present, which makes it either acid, neutral or alkaline, and hard or soft. A fish shop near you will acclimatise the fish you buy to the local water conditions so you can keep them in your aquarium. Some fish, however, can only be kept under certain conditions, and these may be labelled as 'soft water' or 'hard water' species. To keep these more specialised fish, you may need to seek additional advice from your shop.
Tackling water problems.
Most health problems and sudden losses of fish can be traced back to problems with the water conditions. If you experience such difficulties, a few steps will help to bring the aquarium back to normal. Small, regular water changes of up to 20% will help dilute toxins in the water, while stopping feeding for a few days will prevent any more waste being produced. Test your water as soon as any problems arise.
ALL ABOUT WATER
DON'T BE SHY - ASK FOR HELP
If you are unsure about your water conditions for use in test kits, most good retailers will allow you to bring in a sample of your aquarium water, which they can test and explain the results for a small charge.
If you experience water quality problems with ammonia, nitrates, or nitrates, allowing the filter to become a little dirtier than normal can actually help to encourage the useful bacteria to grow.
Water test kits involve taking a sample of tank water, adding a liquid or tablet reagent and comparing the colour change to the chart provided.
NITRATES IN TAPWATER
Some tap water sources contain high levels of nitrates, which can make it difficult to keep levels low in the aquariums. In these cases water changes are still important, but you may also need to add nitrate removing filter media to the aquarium. Nitrates are only dangerous for most aquarium fish above 50 mg/L for extended periods.
Tapwater treated for humans, needs conditioning for aquarium fish. Using tapwater conditioner is a quick and reliable method of neutralising the chemicals added to water to make it safe for human consumption.
Choosing your plants.
There are hundreds of species of aquarium plants to choose from; some will only do well under specialised conditions, while others grow well in all aquariums, so it is a good idea to ask advice when you buy them. A few good species to start of with are vallisneria, hygrophila, anubias, cryptocoryne and Java mosses and ferns. As a very general rule, plants with fine, feathered or red leaves are more difficult to keep.
Most plants are supplied in either bunched or potted form. For potted plants, simply remove the outer pot, leaving the protective wool around the roots, and place the base of the plant just beneath the gravel. Bunched plants usually consist of several individual plants held together by a weight. Remove the weight, separate out the stems and plant each one spread out over a large area.
Creating a display.
You can plant your aquarium in any number of styles, and taking a look at other aquariums may help to provide inspiration. A mixture of shapes, sizes and colours can look just as good as large groups of the same plant. A good display usually consists of taller 'background' plans around the back and edges of the tank, smaller 'foreground' plants for the front and a couple of distinctive 'specimen' plants to provide impact.
Basic plant care
Creating a thriving, fully planted display may take a little extra research, but a few simple tips will help any tank to become a suitable home for hardy plants. The two most important points to consider are the substrate and lighting. The substrate material should be made up of grains between 1 and 2 mm in size – roughly between sand and small gravel, while the lighting should consist of a minimum of two fluorescent tubes. You can improve your tank's lighting by replacing the supplied tubes with brighter or special tubes that encourage plant growth and adding a light reflector.
DO PLANTS CAUSE ALGAE
Since algae often grow on plants, it is easy to assume that plants are the cause of algae problems. In truth plants simply provide a good surface for algae to grow on, since they are in open water, where nutrients are available, and closer to the lights than other surfaces. Once established, plants actually help to combat algae growth by competing for nutrients.
FEEDING YOUR PLANTS
Plants in the aquarium get a large proportion of the food they need from the waste produced by your fish, but the regular addition of liquid plant food or fertiliser tablets will help to give your plants and extra boost. Continue using plant fertilisers while your plants are doing well, but cut back if your tank experiences problems with algae.
TAKE YOUR TIME
Since aquarium plants are mainly ornamental, you can start with a few and add more as the tank matures. This way, you can find out which plants do best, and hopefully leave some room to propagate cuttings from successful specimens.
Filling the tank.
Once your aquarium and any external equipment are in place you can add the substrate (gravel) before filling the tank. Rinse the substrate first under running tapwater to remove any dust. You can also fill the tank with tapwater, but be sure to use the cold tap to avoid adding metals released by some heating systems. If you use a hosepipe, run the water from a few minutes first to remove any old water from the pipe. Thoroughly washing gravel substrate is vital to remove dust and debris that will cloud the water.
GETTING READY FOR FISH
Treating the water
Once the tank is partially filled, you can place the heater and filter in position according to the manufacturer's instructions and check everything is working correctly. It is a good idea to add a dechlorinating liquid at this point to remove chlorine, chloramines and heavy metals from the water. (When carrying out water changes, add the dechlorinator to a bucket of water before pouring into
the tank.) Your tank needs time to settle, warm up and stabilise before you add any fish. During this time you can aquascape the tank and plan which fish you intend to keep.
How soon can I add my first fish?
When your aquarium has been running for a week it should be ready for its first fish. Now the filter will have to start cleaning up the waste fish produce. This process often takes time, since the bacteria need to grow and settle, and the delay in growth rate can cause dangerous fluctuation in water quality. If you have the patience, you can add a bacterial product to the tank for up to a month before introducing any fish. This 'fishless cycling' allows the filter to mature and greatly reduces problems associated with the new aquariums. Only start adding your fish once ammonia and they treat levels have risen and then dropped to zero. Use in a tub for the condition that is a quick and reliable method of neutralise in the chemicals added to water to make it safe for human consumption.
With all the equipment and plants in place, it is tempting to add some fish - but wait at least a week.
CHOOSING YOUR FIRST FISH
Make a list.
Since there are so many different types of fish to choose from, you will need the advice of a good dealer to help you decide which fish to keep.Take a little time to look at all the fish available and make a list of those you like, even if there are too many for your tank. You can then work out which fish will mix together and which will cause problems, eventually ending up with a suitable selection. That way, you will avoid the disappointment of discovering that a fish you want to add later on is unsuitable for keeping with the stock you already have. Have a good look at all the fish in the dealer's tank before making a choice. Buy your fish from a reliable aquatic dealer and don't be afraid to ask for advice.
Choosing healthy fish
Even the best retailers have occasional problems with fish health, so it is important to check the health of the fish before you buy them. Avoid any fish that have cloudy eyes, marks or protrusions on the body, or 'clamped' fins. Most fish should be active and responsive, although some species are naturally quiet, so look to see what the other fish of the same type in the tank are doing. Any individuals that are behaving differently maybe ill.
Transporting and introducing fish
Your dealer should package your fish suitably for transport by placing them in plastic bags with more air than water, if you are travelling for more than half an hour, tell your dealer before your fish are caught so that they can be packaged accordingly. Acclimatising your fish properly is very important and any sudden changes in temperature or light can be very stressful. Don't just tip them straight into your aquarium. To minimise shock, turn off the aquarium lights. Float the unoppened bag in the aquarium. Open the bag by removing seal or band. Roll the bag down from the open top to form a collar so that the bag will float in the aquarium without support. Float the bag for approximately 20 minutes, during this temperature equalisation period, regularly add small amounts of water from the aquarium into the bag. Gently release the fish into their new home. Do not turn on aquarium lights for at least one hour. The fish need to be left in peace to settle in, so wait till next morning to start feeding.
Common and scientific names
All aquarium fish have both common scientific names, but a fish me have several different, names, which can be confusing. When you choose additional fish for your aquarium, you will need to know which fish you already have, so that you can check that any new fish are compatible with your existing stock. It is a good idea to make a note of both the common name and a scientific name of any fish you buy.
FEEDING YOUR FISH
DO YOUR RESEARCH
Although your dealer should be able to advise you about each species of fish on sale, it is always worth double checking with another source or researching your choices with a good fish species book.
HOW MANY FISH?
Working out a correct fish stocking level for your aquarium can be difficult since there are so many varied factors to consider, and new aquarium technology allows greater stock levels than most popular formulas. The most important factor is to stock slowly, adding only a few fish each week, and follow the advice of your retailer.
HOW OFTEN SHOULD I FEED MY FISH?
This depends on their size; small fish require several small feeds a day, whereas large fish require a more substantial feeds less often. In the case of a community of small fish, steadily increased the feeding as the tank matures. Start with one feed every other day for the first week and increase this to 2 or three small feeds a day after a few months
A good diet is vital
The phrase 'you are what you eat' applies equally well to fish; a good diet will have a marked effect on their overall health, colour and disease resistance. Always feed your fish on 'name brand' food; although they may look the same, cheaper alternatives have a far lower vitamin content, are made from inferior quality ingredients and will produce more pollutants in the aquarium.
Overfeeding is unkind to fish
The absolute golden rule in fishkeeping is to avoid overfeeding, and this is where most fish keepers have difficulties. Because almost all the waste produced in an aquarium can be traced back to the food, whether it passes through the fish or not, any overfeeding will cause excess pollution, which results in cloudy water, ill health and a whole host of water quality problems. When you offer your fish food, they should eat it all within one minute. Anything left over or that sinks to the bottom constitutes overfeeding. Always remove uneaten food from the tank.
Are varied diet is more interesting
Different fish require different types of food, so a varied diet is essential. However, during the first month it is best to stick to simple flake food to avoid any excess waste. After this time, continue to offer a flake food as the main part of the diet, since it contains all the essential vitamins and minerals, but supplement the flake with frozen, live, pellet and freeze-dried foods. Sinking wafers and pellets are also available for bottom-dwelling fish, but make sure none is left to decay in the tank.
Many fish relish occasional treats of fresh fruit or vegetables; some algae eaters, in particular, enjoy grazing on a slice of cucumber. You can buy clips, often called 'lettuce grips', to hold items of food. Place these in a part of the tank where you can see them and remove them easily if the food is not eaten. Only ever feed fresh food items and not manufactured foods and remember that these are only supplements to a proper diet made up of specially paired dried foods. Some fish enjoy fresh peas with skins removed, cucumber, courgette and blanched lettuce secured in a clip
WHEN TO FEED
Your fish will become used to being fed at set times of day that suit your schedule. Some bottom-dwellers maybe semi-nocturnal and feed best in the late evening, while other fish should be fed between one hour after lights on and one hour before lights off.
Why do water changes?
There are two main reasons for carrying out regular water changes in the aquarium: one is to reduce the build up of nitrates – the end result of filtration – and the other is to replace lost minerals and nutrients that help to stabilise water conditions. The volume and frequency of water changes depends largely on the level of nitrates in the water, so regular water testing is essential. As a basic guide, aim to replace 10 to 20% of the water every two weeks. Take new water from the cold tap, treat it with a dechlorinator and leave it to warm up to room temperature before using it.
Cleaning the substrate
A large proportion of aquarium waste will settle in the substrate. Live plants in aquarium use this waste as a source of food, but in open areas in can built up to dangerous levels, encouraging algae and a deterioration in water quality. Using a gravel cleaning device you can disturb and siphon the waste from the substrate. Discard the water removed by siphon or, even better, use it in the garden or on house plants and count it as a water change. Always remember to turn off the electricity supplies before carrying out any work in your aquarium.
Establishing the routine
Maintaining a typical community aquarium is relatively easy providing it is done regularly. Creating a weekly routine will help to achieve this aim and reduce the overall time you spend on the aquarium. A basic routine would consist of cleaning algae from the glass, gravel cleaning, rinsing filter sponges ( in the waste water from gravel cleaning) and topping up with water prepared the day before.
Keeping filters clean
You filter will need regular maintenance to remove trapped waste matter and to keep it in good working order. Clean internal filters every two weeks and external filters once a month. Always rinse sponges and other media in water taken from the aquarium, since the chlorine tapwater will damage useful filter bacteria. If your filter contains carbon, replace this every few months. The main sponges or biological media will only need replacing once a year . To ensure that bacterial populations remain suitably high, never change more than half the filter's sponges or biological media at any one time.
Avoid stress and poor water conditions.
Stress is the biggest cause of disease in the aquarium and can result from a number of factors, including transportation, sudden changes in water conditions, inappropriate decor, aggression from other fish and fluctuations in heating levels. Poor water quality can trigger health problems because the fish's immune system overreacts to pollutants in the water and continually fights a losing battle. Always remedy the cause of any disease before treating the symptoms, because as long as stress or poor water quality factors are present, treatments are often ineffective.
Check your fish for signs of ill health
Under normal conditions, the fishes' immune system prevent diseases taking hold, but problems occur when a fish becomes stressed, is physically injured or when the background levels of harmful disease organisms rise dangerously. Taking care not to overstock the tank, quarantining new fish, monitoring water conditions and good aquarium maintenance will prevent the outbreak of most diseases.
Making the most of treatment
Before using a treatment, carry out basic maintenance and remove any carbon or chemical media from the filter, since these will also absorb treatments. Some treatments can decrease the amount of available oxygen in the aquarium, so keep the water surface moving as much as possible to increase aeration. Always carry out the whole course of any treatment you use according to the manufacturer's instructions. Some diseases have a 'life cycle' and a full course of treatment is designed to prevent reinfection. After using a course of treatment, carry out a small water change and replace any carbon or chemical media. Avoid using two treatments at the same time, as the combined effect of many common treatments can be dangerous, although you can continue to use dechlorinators or plant fertilisers.
In the wild, fish do not always find food every day and adult fish are perfectly capable of surviving happily for a few days without feeding. For longer periods you can use holiday food blocks or automatic
feeders. If you leave someone
else in charge of feeding, make
sure they know exactly how
much to feed, since
non-fishkeepers are likely to overfeed.
KEEPING FISH HEALTHY
LITTLE AND OFTEN
Aquarium maintenance is essential, both for the filters' long-term health and the appearance of the aquarium, but should always be done in small steps. An aquarium is a balanced environment that needs time to mature and establish, so avoid any major upheavals as much as possible.
As you guide the cleaner over the substrate, the gravel is sucked up into the tube and whirled around in the water flow to separate it from any debris. The heavier particle sink back down to the floor and the more buoyant silt is sucked into the bucket.
Never use collected rainwater in the aquarium. Although it is often purer than tap water, it contains none of the essential minerals needed to maintain stable water conditions. Also, it can contain pollutants picked up from the atmosphere after dry spells, and may even have passed through dead animals in the house guttering.
WHO SHOULD I BELIEVE?
Aquarists are often given conflicting advice on the subjects of water changes and filter maintenance. This is because the correct maintenance for your tank may be different to that of another tank of the same style and size. Regular water testing and advice of a good dealer will help you achieve the right level of maintenance.
A common method of treating fish is to set up a separate 'hospital tank', where affected fish can live in isolation while they are treated. This will only work if the tank is set up with water from the main aquarium and with a matured filter. Adding hiding spots will also aid recovery.
Diseases usually take time to affect fishes; look out for signs such as loss of appetite accompanied by obvious physical symptoms. However, sudden deaths are usually the result of pollutants in the water that may not be easy to test for. You can buy special 'polishing' media for filters to remove unusual pollutants.
It is a good idea to wait at least a few weeks after any outbreak of disease before restocking. New fish are heavily weakened by the process of transport and acclimatisation and are more likely to be affected by anything left in the water that could cause disease.
Decorating your aqaurium
You can now begin to decorate your aquarium with rocks ornaments and plants. There are 1000's of different options available for you to choose from. Any heavy rocks should be placed carefully in your aquarium to prevent damage. In nature, fish depend on retreats such as wood, rocks and plants for safety, and many avoid bright areas so that they are not visible to predators. Without a suitable environment in the aquarium, they become stressed and uneasy, which in extreme cases will result in disease and even death. When decorating your tank, try to create as many different areas as possible for your fish. There are many artificial, but natural-looking, ornaments on sale, designed specifically to provide hiding spaces but don't clutter the aquarium, leave some swimming space for the fish.