Establishing Your Freshwater Aquarium (2021 FAQ Part 2)


Where should I put my aquarium?

There are no set rules about where you should put an aquarium, but there are definitely a few things to avoid, namely: Direct sunlight since this will promote algae growth, and can lead to the tank overheating in hot weather. Draughts, fumes & aerosols, particularly in open tanks or bowls. Draughts in cold weather can cause the temperature of a tropical tank to drop or fluctuate, both of which are undesirable. Fumes from cooking can leave a film of oil over the tank which prevents air exchange. Many aerosols (fly sprays etc) are extremely toxic, and should not be used near an aquarium. Knocks and bumps, apart from the obvious (but low) risk of tank breakage, stress the fish and can make them more prone to disease. Some fish can even die from shock, or they may dart about with the risk of injury, or even jump out of the tank. There are a few other factors you may want to consider. For example, you will probably not want to place your tank too close to electrical equipment, as there is always the chance of splashes and water spillage. However, it will usually need to be close to a power supply for plugging in the filter etc. If relying on an air-driven filter, it is not a good idea to have the tank in a bedroom, since the air pump can be noisy. Finally, you will want your tank to be somewhere where you can appreciate it, such as a living room, rather than tucked away in a room that’s never used.

What water should I use?

In most cases, tap water treated with a good quality chlorine neutralizer is the best choice. Tap water generally has a neutral to slightly alkaline pH (eg 7.0 to 7.4), which is desirable for an aquarium. Although in their natural waterways many fish, particularly tropicals, occur in slightly acidic waters, most are happy at or around a neutral pH (between 6.5 and 7.5). Bear in mind that fish you buy from your local store are already being housed in, and are adjusted to, the local tap water. Also, since fishes waste products make the water more acidic (lower pH), doing water changes with slightly alkaline water will help to keep the pH balanced. Finally, although chlorine is detrimental to fish, it is added to tap water to destroy pathogens (disease-causing organisms) and so is desirable from this point of view. Of course, chlorine must be removed before the water is added to the aquarium, this is quickly and easily achieved by using a chlorine neutralizer, often called a water ager or water conditioner. If your tap water is extremely alkaline, or you rely on bore water, you may want to mix some rainwater with your supply. Rainwater is generally soft and slightly acid. However, rainwater cannot be recommended unreservedly for a number of reasons. In city areas, rainwater may be contaminated by atmospheric pollutants, fallout, and droppings on rooves where it is collected, and even by the material dissolved from the insides of the rainwater tank. Also, for the reasons outlined above, it is generally best to have slightly alkaline, rather than acidic water as a baseline. Other types of water that may be available include spring water, filtered water, demineralized, softened, and reverse osmosis water. These are usually not suitable. Spring waters usually contain a range of dissolved mineral salts that are not suitable for fish keeping. Filtered, demineralized and RO waters are actually too pure for most fish, and some softened water contains high levels of sodium. However, some may be useful. In particular, RO, demineralized, or highly filtered water can be used instead of rainwater to soften and lower the pH of unsuitable tap or bore water. If your water filter contains only carbon and or a mechanical filter, then the water produced by this will be acceptable for use with fish. If for any reason, you are using water that differs from the water used in the store, you must acclimatize the fish very slowly to the different water. Either place the fish in a bucket with the water they came in, or leave them in the bag, and over the course of approximately 2 hours, add a little of your tank water at a time until the fish are in primarily tank water. They can then be introduced to the aquarium. In no case should you use hot water from the tap or kettle as this contains dangerous levels of metals and dissolved gases? It is recommended to let the tank run for at least a day or two before adding fish as this should ensure suitable temperature, but if you must add fish straight away, choose species that can tolerate cold water and take some extra time to acclimatize them.

Do I need to add anything to my water?

The most important thing you need to add to new tap water is a chlorine neutralizer. Why neutralize chlorine? Many people will state that they have kept fish in tap water with no water conditioner and had no problems, however, they are also puzzled when their fish die after a few months for no apparent reason! Putting a fish once, or even twice into tap water with an average concentration of chlorine will cause it no great damage, however, the effects of chlorine are cumulative, and repeated exposure will lead to gill damage and anaemia, with death following eventually. Higher concentrations of chlorine, which may be used in the water supply from time to time, can cause greater damage and stress or even death, particularly in sensitive species, and chlorine will also harm filtration bacteria, leading to a rapid decline in water quality. For these reasons, it is highly recommended to use a chlorine neutralizer whenever new tap water is added, although only the water being added needs to be treated, not the entire tank volume. Chlorine will eventually dissipate from water that is stood in a bucket, and this method of water aging is still widely practiced. However, it does have its drawbacks. Water changes must be planned well in advance, and it is impossible to neutralize chlorine this way if an emergency water change is needed. Also, when higher levels of chlorine are present, the time required for dissipation will be longer and is not easily measured. If chloramines (a chlorine-ammonia compound) are present in your water supply (and their use is expanding rapidly), they will not be removed by standing the water. Adding a basic chlorine neutralizer will break the chlorine-ammonia bond and remove chlorine, but a high concentration of ammonia may remain. There are a number of water conditioners designed for use where chloramines are present, and these remove both chlorine and ammonia. If you are unsure what is in your water, these products are strongly recommended. Even if chloramines are not present, the use of more advanced water conditioners is still a good idea, as they can also be used to control ammonia produced by the fish. Apart from chlorine neutralizer, there is nothing else you have to add to your water. As discussed above, it is usually not necessary to adjust pH or water chemistry. You may wish to add a half dose of a broad-spectrum medication as a disease preventative, however, the best preventative is simply to maintain good water quality. If you have problems with algae, you may wish to add an algicide, or if growing live plants, liquid fertilizer can be added. Many other treatments are available to help improve water clarity and chemistry, and of course, there are medications to treat disease. However, rather than using these indiscriminately, it is best to work out what is going to best suit your specific needs.

What temperature should the water be at?

If you are keeping tropicals, make sure the temperature has stabilized and is correct before adding fish. For most species a temperature of 26°C is ideal. The range in which most tropical fish are comfortable is between 24°C and 28°C, and most will tolerate temperatures between 22°C and 30°C. Aiming for the middle gives the most room for fluctuations on very hot or cold days. Use an aquarium thermometer to measure the temperature, not the heater’s own thermostat. When performing small water changes on a tropical tank (25% or less) it is usually not necessary to adjust the water temperature since the effect on ambient temperature when adding slightly cooler water to a tank is minimal. Using water from the hot tap or that has been heated in a kettle is most definitely not recommended, as this water contains dangerous dissolved gases and metals! If the tap water is very cold, let it stand and reach room temperature or heat it with an aquarium heater. For coldwater fish, the temperature is not so important, but should not be completely ignored. If setting up your tank or doing a large water change on a very cold day, let the water reach room temperature or acclimatize the fish by floating them in a bag for about half an hour. On very hot days, the temperature should ideally not exceed 30°C. Be sure that your aquarium is well-aerated, especially on hot days, since warmer water holds much less oxygen.

What type of fish should I put in first?

A newly set up aquarium contains very little filtration bacteria, and so you should start by adding only a small number of hardy fish. For coldwater, one or two small goldfish, or a few smaller fish (eg danios) is a good start. Since most coldwater fish are fairly hardy, the choice of species is not so important. In a tropical set up, your choice of first fish will depend on two things. Firstly, you need hardy fish, and secondly, you need fish that will be compatible with the species you eventually intend to keep. It is important to think about what type of fish you would like before adding fish, since not all are compatible. If you are setting up your first tropical tank, you will probably want to keep as many different species as possible. In this case, you will want to get community fish, ie those that are not territorial, predatory, or aggressive. Probably the best first community fish are livebearers, particularly swordtails, platies and mollies. These are hardy, peaceful and colourful fish, and they also like slightly alkaline water (which you will usually have in a newly set up aquarium). Other good first fish are barbs, danios, tetras, gouramis or rainbows. These groups contain many suitable species, see our species guide for more details. Fish which are generally not recommended as first fish for community tanks include delicate species (eg some tetra species, silver sharks, loaches), many cichlids (although some are not particularly aggressive and can be used), sharks, grunters, and other large or aggressive species, and catfish. Although many catfish are very hardy, most are either algae eaters or scavengers, and in a newly set up aquarium there is often not enough for them to feed on. If you are not interested in community fish, and instead want fewer but larger and brightly coloured fish, then cichlids may be the fish for you. If you do decide to keep cichlids, be sure to research the species you are interested in, and decide on compatible types. It is easiest and best to buy these types of fish at a small size and let them grow up together. Since most are hardy, the best species to put in first are the least aggressive varieties of those you want. Let these settle in first, and gradually add the more aggressive species, adding the most aggressive last. Try to mix fish of a similar size only. It is best to start with only a fraction of the number of fish your tank will eventually house, generally, no more than a quarter (ie if you intend to get about twenty fish, start with five or less). The tank will look empty to begin with, but this is preferably to having a tank full of stressed and disease prone fish! Build up the number of fish in your tank gradually over a period of a few weeks to a few months. The filtration bacteria will increase in accordance to the number of fish, but this takes time, so never add more than a few new fish at once. In your filter it will take a few weeks for the bacteria to establish and start growing, so take extra care with feeding over this period, and do not be surprised if your water is not quite crystal clear.

How should I transport and acclimatize my new fish?

The store you buy your fish from will pack them in plastic bags with a little water and as much air as possible. On cooler days, most fish will survive in a bag like this for quite a few hours, but be sure tropical fish do not become chilled. On warmer days, chilling is not a problem, but the water will hold less oxygen and the fish will suffocate if left bagged up for too long. The water can also quickly become too hot: never leave a fish in a bag in your car or in direct sunlight! It is best not to transport fish in very hot weather although short trips in an air-conditioned vehicle or using an insulated container (eg esky or foam box) will probably cause no harm. In any case, despite the fact that fish will survive being in the bag for reasonable periods, it is best to get them home as quickly as possible, since this will cause the least stress. Once you have brought the fish home, float their bag on top of your aquarium for about 15 minutes. This will allow the temperatures to equalize. If the water in your aquarium is of the same quality and composition as the store’s water, the fish can now be released. If however, you are using rainwater, or water that has been modified or is different from the store’s water it is best to gradually add the water from your aquarium into the bag a cupful at a time over about 2 hours. This lets the fish adjust to the different water quality. If you have other fish in the tank, feed them a small amount as you release the newcomers to distract them. If you have aggressive fish, you may need to use some extra tricks to be sure the new arrivals are not harassed. Do not feed the new fish for at least 24 hours, and give them peace and quiet in which to settle down.

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