Introduction:
Keeping aquarium or “ornamental” fish as pets in aquaria or garden ponds is becoming an increasingly popular pastime in NSW. Many hundreds of fish species, both native and exotic, are sold for this purpose by aquarium suppliers and it has been estimated that this industry is worth $350 million annually in Australia.
Keeping ornamental fish is a great hobby for people of all ages, however it is important to make sure your aquarium and its inhabitants remain happy and healthy. Here are a few things you should remember: * Know your fish – Some need special conditions and diet, while others are aggressive and unsuitable for a community tank. * Change the water – Replace about a third of the water in your aquarium at least once a month. Tap water may contain chemicals that harm your fish so make sure you add a water conditioner available from your pet shop. * Remove sick fish – Diseased fish can contaminate others so remove them quickly. * Don’t overfeed – Feed only as much as your fish will eat in one minute and just once a day, or as advised by your pet shop. * Don’t overcrowd – Overcrowding increases pollution and aggression problems.
Testing Aquarium Water:
Water chemistry is not visible; therefore, it is vital to check it on a regular basis. The best way to make this a routine is to check on the tank chemistry while changing the water.
The vital parameters are pH, nitrates, nitrites, and carbonate hardness (salinity for marine tanks).
Stability is the main factor with pH. pH in the range of 6.5 – 7.5 is suitable for most species, but they can adjust if slightly out of range.

KH (carbonate hardness) is the indicator of pH stability. It should be kept under close observation if it comes close to 4.5 dH (degree hardness) or 80 ppm. You must take action if it decreases any further.

Half a teaspoon of baking soda per twenty-five gallons of water will raise the kH by about 1 dH (17.8 ppm).

Nitrites should be undetectable at all times (except during cycling). If you detect nitrites make sure you check on ammonia as well.

Nitrates should be kept below 10 ppm in freshwater and 5 ppm in marine and reef (preferably 0 ppm).
Aquarium Filtration
The proper function of the filter is essential. Filter inserts (floss, Algone, activated carbon) should be changed at least every four weeks. A high fish load may require shorter periods. Trapped particles will decompose in the filter as they would in the tank. The filter should also be cleaned once a month (do not touch the bio-wheels, if present) by using the water extracted from the tank during the water change.
Recommended Aquarium Maintenance Routine
Daily
Make sure the equipment is running properly.
Watch your fish during feeding. Behavioral changes are a good indicator of a potential problem.
Weekly
Count your fish. In case of fish death, smaller species can decompose quickly, resulting in ammonia and nitrite spikes, and eventually high nitrate levels.
Every Other Week
Test your water for the vital parameters: pH, carbonate hardness, nitrite and nitrate.

Change 10-15% of the water .

Vacuum the gravel .

Clean the aquarium walls. Filter floss is fairly cheap and very efficient. Start from the bottom upward and rinse out often.

Rinse filter inserts (cartridges) with the extracted water.
Monthly
Replace filter inserts, cartridges, floss, carbon, and Algone.

Inspect tubing, connections, airstones, skimmers and other parts for proper operation.

Clean aquarium top to assure your lighting is not affected.

Check the expiration dates printed on the boxes and bottles of the aquarium supplies you use. Do not use after the imprinted date. Expired test kits will give false readings and may prompt you to take unnecessary action. Aquarium Aeration:
Proper aquarium aeration is one of the most important things to consider in setting up any aquarium. Low oxygen levels are more common - and dangerous - than often realized. Use an air pump to bring fresh oxygen into your tank and power certain equipment. Add air stones to aid in circulation and create beautiful displays of shimmering bubbles.

If you have a large tank, consider supplementing your aeration system with a water pump or powerhead that will aid in properly circulating the oxygen through your entire tank. |

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Water Changes:
One of the most important aspects of successful fish keeping is good aquarium maintenance, including routine water changes.

Fig: Cleaner
Why?
An aquarium looks beautiful and the water is crystal clear, everything is wonderful. * In an established aquarium, bacteria convert ammonia (produced mainly by decaying food and fish waste) to nitrite, and nitrite to nitrate (NO3). Nitrate is the end result of the Nitrogen Cycle, and while it is the least toxic form of nitrogen it does build up over time – to potentially dangerous levels if left unchecked. Changing a portion of the aquarium water on a regular basis is the easiest way to reduce it. * The buildup of nitrates (nitric acid) can reduce the alkalinity of your water, potentially resulting in a pH drop. * Phosphates, pheromones and other chemicals can build up between water changes. * Minerals and trace elements are depleted over time, which can result in a GH drop. * Poor water quality puts stress on fish, which is often the root cause of fungus and parasite problems * It has been said that dirty water holds less oxygen, although I do not have any scientific data to back this statement up. Without question, water changes supply clean oxygenated water to your fish – and that’s a good thing!Poor water quality can lead to infection on a wounded fish.

Procedure: 1. If you wish to vacuum the gravel at the same time (a very good idea), remove any rocks or other decorations you want to vacuum under (be careful there aren’t any fish hiding in the nooks and crannies!) Many people opt to do this on a rotating schedule; Week-1 water change only, Week-2 water change and gravel vacuum, etc. If you have an undergravel filter system you will likely have to vacuum more frequently to keep nitrates at bay. 2. If you have excessive algae growth on any decorations and wish to remove it, you can soak them in a weak solution of chlorine bleach and water (1 or 2 tablespoons bleach per gallon of water will suffice). Since some of your beneficial bacteria lives on the surface of these decorations it’s not advisable to do this too frequently, or at the same time you replace filter media. Also keep in mind that the green algae is highly nutritious and many fish (including Mbuna and Plecostomus) will feed on it. 3. If you want to scrape algae off the glass this is a good time to do it. Use a non-scratching brush or sponge used only for your aquarium, and be certain it does not have any detergents or other cleaning agents imbedded in it by the manufacturer. 4. Pre-measure your water conditioners (buffers, dechlorinator, ammonia neutralizer, etc.) for the amount of water you intend to change. You can do this in a bucket or other clean container used only for aquarium maintenance. (See "Water Treatment" for details on making tap water safe, and "Practical Water Chemistry" for information on buffering and other chemistry tips.) 5. Unplug aquarium lights, filters and heaters. (Some people advise doing this before working in the tank to avoid the possibility of electrical shock if, for example, the heater were accidentally smashed. I prefer to at least leave the filters running to pick up some of the muck stirred up in Steps 1 thru 3.) 6. Start the water siphoning. You can measure the volume removed by collecting it in a pre-marked container (large bucket or plastic trash can) OR by pre-measuring and marking an indicator on the tank to which you consistently bring the water level down. If you use the second method, you may still wish to collect some of the tank water in a container so that you can rinse filter media in it. (The chlorine in tap water as well as a fluctuation in temperature can destroy beneficial bacteria.) * For gravel substrate, a Python® type hose is ideal. Simply plunge it into the gravel and slowly pull it out. Debris is sucked up with the water, while the gravel falls back to the bottom. It is a common fallacy that vacuuming too thoroughly will remove beneficial bacteria. In truth, bacteria adhere to all the surfaces in your tank including the glass, substrate, rocks, plants and filter media. It is not in the muck you remove from the gravel. * For sand substrate, move your siphon hose or Python® in a circular motion just above the surface to pick up debris without sucking up the sand. You could also use a second tool (such as a PVC pipe or your other hand) to disturb the sand just before passing over it with your hose. 7. Once you have removed the desired amount of water, replace your rocks and other decorations. (If you cleaned them in a bleach solution you must rinse thoroughly, until you can no longer detect the smell of bleach. After that, you can submerge them in fresh water with a dose of dechlorinator as an additional precaution.) 8. Now you can begin refilling.
If you are using water straight from the tap, allow it to run for at least 5 minutes to reduce the concentration of copper and heavy metals from household plumbing. You can use this time to adjust the temperature as close as possible to that of your aquarium. A thermometer first placed in the tank then taken to the water source is very helpful. (There are claims that warm or hot water from your tap should not be used since it tends to have a higher concentration of copper and heavy metals 9. Restore power to your filters, heaters and lights. 10. Record your activity in a maintenance log.

Biological Aquarium Filtration:
The third type of filtration -- biological aquarium filtration -- is the most important of all. The lack of effective biological filtration is probably responsible for the deaths of more fish than any other cause. The particular dissolved compounds controlled by biological filtration are very toxic to fish even at low concentrations.
In newly set up tanks, the effects of these compounds can kill fish very quickly. In aquariums that have been running longer but are overstocked with fish, there can be constant low levels of these compounds in the water. This creates chronic, long-term physical stress, resulting in diseased and dying fish.
To understand biological filtration, it is necessary to understand a basic process in the aquarium: the nitrogen cycle. Ammonia is one of the key elements in the nitrogen cycle. Fish produce ammonia directly both as a by-product of respiration and as a waste product from the digestion of foods.
Solid wastes are also converted into ammonia, which is why it is important to remove them with mechanical filtration. Uneaten food, plant materials, and other organic items that decay in the tank are also converted to ammonia.

Fig: filtration for fishkeeping.

Ammonia, a nitrogen-based compound, is extremely toxic. In an aquarium, it can build up quickly and threaten all the fish in the tank.
Nature, as usual, has a solution to the problem. A species of bacteria known as Nitrosomonas will actually consume ammonia, as long as there is enough dissolved oxygen in the water to support the bacteria.
Nitrosomonas bacteria are everywhere, so you don't even need to add them to the aquarium; they will grow there naturally. However, it takes them a while to multiply to a population size capable of consuming all the ammonia in the water.
As the Nitrosomonas consume the ammonia, they convert it to nitrite. Nitrite is also toxic to fish and in the long run tends to be a larger problem than ammonia.
Another species of bacteria, Nitrobacter, will consume the nitrite and convert it to nitrate, a relatively harmless compound that can be used up by plants and algae.
As with Nitrosomonas bacteria, it takes some time before the Nitrobacter are able to multiply to sufficient numbers to handle all of the nitrite. Unfortunately, until the Nitrosomonas are able to increase to numbers sufficient to control the ammonia in a new aquarium, the high ammonia levels inhibit the growth of Nitrobacter, thus allowing the nitrite levels to increase quickly and remain high.
While it may take a week or less for the population of ammonia-consuming Nitrosomonas to grow to sufficient numbers, the delay in Nitrobacter growth means it can be six weeks or more before nitrite is under control.
This process of starting the nitrogen cycle, which generally takes a total of six to eight weeks, is known as "breaking in the tank." If there are too many fish in the tank during this process, and not enough water changes are made, many of the fish will die.
This situation is known as "new tank syndrome." It's also the reason so many new hobbyists are unable to keep their fish alive and healthy.
Some aquarists report that they successfully break in their tanks using fish, but add a one-step water conditioner that neutralizes the toxic ammonia. The neutralized ammonia can still be consumed by the Nitrosomonas bacteria so they can multiply, but it will pose no danger to the fish.
However, the Nitrosomonas bacteria will still produce nitrite, and the fish will have to battle the increasing concentrations of that chemical until the Nitrobacter colony is established.
The end product of the nitrogen cycle -- nitrate -- will not harm fish unless it reaches rather high levels. Because nitrate can be used by plants as food, live plants will help control nitrate levels. Without aquatic plants, however, the nitrate will be used as food by simpler plants -- algae.
One way of controlling problems with excess algae is to lower the nitrate level by making partial water changes, which should be a normal part of aquarium maintenance anyway.
Check out the next section to learn about aeration and surface agitation.

Conclusion:
Good aquarium maintenance practices will lead to a healthy aquatic environment and thriving fish, providing years of joy for the hobbyist.
Expensive and time-consuming problems can be prevented by spending thirty minutes on maintenance every other week.
The biggest factor for maintenance is tank stability. As long as everything is running properly and your fish are healthy, there is no need for any major change, even if the pH or hardness seems to be slightly out of range; only increases or decreases of the major water parameters will need your careful but immediate attention.