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How to Start Your Aquarium Properly

How to Start Your Aquarium Properly 2

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Before Filling the Tank

Getting into the world of aquarium keeping is not something to be done on a whim. Just like any other pet, fish are a responsibility that cannot be neglected once taken on. They are living beings whose existence and survival depend on the aquarist and how well they fulfill their duty. Although the obligations are limited and the daily care required is not overly demanding, it is crucial not to overlook them, as it could result in the demise of the fish.

Similarly, setting up and maintaining a tank involves expenses that cannot be avoided. These costs will depend on various factors such as tank size, biotope, plants, etc., but a minimum investment is necessary.

The first question to ask yourself is, “Am I ready to invest time and money into this venture?”

If your answer is “Yes,” then welcome to our wonderful world of enthusiasts.

How to Start Your Aquarium Properly

The Tank, Aquarium

The tank and its choice are of great importance. Without going into too much detail, let’s simply say that “bigger is better” within reasonable limits, of course. A 240L tank will require roughly the same amount of maintenance as a13.2 gallons tank, but it will be easier to maintain balance in a 63.4 gallons tank than in a 13.2 gallons tank. Moreover, larger volumes offer more possibilities compared to smaller tanks. Additionally, many small fish are active swimmers and require a significant area for free movement (a minimum of 23.6 inches). An 31.5 inches wide, 11.8 inches deep, and 15.7 inches high tank is a good starting point for beginners.

A few words about “fish bowls” or goldfish globes. Despite the popularity of these types of aquariums in our society, it’s important to know that keeping a fish in a bowl is considered animal cruelty in many countries. Even if it’s not the case everywhere, it’s best to avoid using these bowls for fishkeeping as they are unsuitable for maintaining fish.

The placement of the tank should also be carefully considered. Obviously, due to its weight, the tank must be placed on a sturdy support (a 15.9 gallons tank already weighs 176 to 198 pounds when filled, while a 63.4 gallons tank can weigh around 771 to 882 pounds!). The stability of the support is also a factor to consider. An unstable support cannot sustain a tank. Moreover, it’s advisable to avoid placing the tank in a frequently trafficked area for the comfort of our fish. Fish are stressed most of the time in such situations, and stress can lead to illness. It’s also recommended to prevent excessive sunlight exposure to avoid excessive algae growth.

In conclusion, a minimum tank size of 26.4 gallons, rectangular in shape, situated in a calm and showcased location, is a good foundation for our future endeavors.


The maintenance requirements and the range of tank options depend heavily on the equipment available. While some fish, like goldfish for example, are less demanding than others, a minimum set of equipment is always necessary. In general, the basics include sufficient lighting (T8 or T5 fluorescent tubes, HQI or HQL lamps), an appropriate filtration system (internal sump, internal or external filter), a heating system (heater or heating cable), maintenance tools (scraper, net, gravel vacuum, siphoning tube, bucket, etc.), and most importantly, a water test kit (we will discuss this further later on).

Furthermore, depending on the aquarist’s desires, other elements may be necessary and can be added to the list. An osmosis unit can produce the required amount of osmosis water for water changes, a CO2 injection system will benefit those who love well-planted tanks, an automatic top-off system can compensate for water loss due to evaporation, etc.

The cost of this equipment depends on the type of devices, brands, power ratings, etc. Some brands have proven their reliability over the years, but new products with more attractive prices are constantly emerging in the market.


Water is undoubtedly one of the most crucial aspects of aquarium keeping. Each exotic fish available in the market has specific water requirements. These needs must be met to ensure the optimal well-being of the fish. The key parameters to know are as follows:

pH (hydrogen potential), which represents the concentration of hydrogen ions (H3O+) in the water. The measurement scale ranges from 1 to 14, with neutrality at 7.0. The higher the pH, the more basic the water is considered, while lower pH values indicate acidic water. In aquarium keeping, pH levels can range from 5.5 to 8.5, or even 9.0 for certain species.

KH (carbonate hardness) measures the concentration of calcium and magnesium carbonates and bicarbonates in the water. This measurement provides an indication of the water’s buffering capacity. Higher values indicate greater stability in the water parameters.

GH (general hardness) measures the overall hardness of the water, which is the concentration of magnesium and calcium ions. Water is considered very soft when the hardness is around 5 degrees GH, soft when it is around +/- 10 degrees GH, and hard when it exceeds 15 degrees GH.

These three values are important and should be known right from the start of your aquarium journey. They need to be regularly tested as well because tap water parameters alone will significantly limit the possibilities available to the aquarist.


Before planning the fish population, questions regarding fish compatibility with the water, compatibility among the fish themselves, overpopulation, and whether the fish are suitable for the tank volume should be addressed.

“Which fish are compatible with my tap water?”
As discussed in the previous chapter, pH and GH measurements will have a significant impact on the choice of fish population. The fish must be able to thrive in the tap water available. A freshwater fish adapted to an acidic environment cannot survive in water with a pH of 8 and GH of 17. It is possible to modify the parameters of tap water, but this operation is not advisable for beginners.

“Are my fish compatible with each other?”
Some fish need to live in pairs, others in trios, some in groups of 5, and others in schools. All these constraints must be considered before purchasing fish. A fish that lives in a school will be stressed if kept alone, and a fish living in a pair will become aggressive towards its conspecifics if kept in a large group. Furthermore, inter-specific relationships between fish vary greatly from one species to another. Some fish, like cichlids, are territorial, while others, such as male bettas, cannot tolerate the presence of a rival male of the same species. Calm fish can be stressed by active fish, and so on. All these behaviors will affect the quality of the fish’s relationships with each other and can transform your tank into either a boxing ring or an aquatic paradise, depending on the cases.

“What is overpopulation?”
A tank is considered overpopulated when it has too many fish, but this notion is subjective. A minimalist rule that applies in many cases suggests “1 cm of fully grown fish per liter of actual water.” This rule generally works for most small fish but needs to be adapted on a case-by-case basis for larger fish or cichlids, for example.

“Is my tank suitable for this fish?”
Some fish sold in stores are small in size (a few centimeters), but they can grow up to 11.8, 15.7, or even 19.7 inches as adults. It’s evident that such fish cannot thrive in a tank with dimensions of 23.6×11.8×11.8 inches. They would barely have enough room to turn around.

Having a good understanding of the fish that interest us helps answer all these questions and prevents many disasters.


Plants play a crucial role in a tank. Not only do they help transform harmful substances present in the water, but they also contribute to the oxygenation of the tank, provide shelter for certain fish, and serve as food for various herbivorous fish.

Therefore, it is essential to carefully plan the planting of the tank before filling it with water. However, it’s important not to forget that plants also have nutritional requirements (nutrient-rich substrate, fertilizers, CO2, etc.) and require specific attention during aquarium maintenance (pruning, propagation, nutrient supplementation, etc.).

During Tank Filling

Once the tank has been chosen, the placement decided (it’s easier to move an empty tank than a full one!), the equipment purchased (make sure everything is functioning properly before filling the tank), the plants prepared, and the water allowed to rest (chlorine evaporation and binding of heavy metals), the actual tank setup can begin. To do this, the tank must be assembled and stabilized on its support (using a polystyrene sheet), the substrate must be prepared and placed (sand or gravel should be rinsed thoroughly), the decorations must be arranged (stones and roots should be cleaned properly), the plants should be planted, and all equipment (filtration, heating, lighting, etc.) should be installed. Finally, the water can be added to the tank.

Then, it’s time to connect everything and move on to the next steps.

Water Chemistry

The next phase is perhaps the longest part of setting up a tank. An aquarium represents an ecosystem in which living beings will thrive. This ecosystem requires balance and harmony, which takes time to establish.

Let’s start from the beginning. Fish, plants, and all the living organisms in the tank produce waste in the form of ammonia or ammonium. At this stage, these waste products are extremely toxic and must be eliminated as quickly as possible. This transformation is facilitated by a colony of bacteria (Nitrosomonas bacteria), which convert the waste into nitrites. However, nitrites are also toxic to fish, even in small amounts, and they must be eliminated as well. This is the role of denitrifying bacteria in the tank. Finally, nitrates resulting from the denitrifying bacteria’s action serve as nutrients for plants, and the cycle begins anew.

This cycle is known as the “nitrogen cycle” and is necessary before introducing any fish, as it allows them to survive. The four weeks following the tank setup should be dedicated to waiting for the nitrite peak and its subsequent disappearance. This phase indicates that the colony of denitrifying bacteria is sufficient and capable of handling the tank’s pollution.

During this waiting period, it is not necessary (and even discouraged) to perform water changes. The aquarist can take this opportunity to make some adjustments to the decor, add or remove plants, etc.

After Tank Setup

Introducing the First Fish

Once the cycle is established, the exciting moment of introducing the first fish is approaching. This long-awaited moment marks the end of the waiting period and can either be the beginning of an adventure or its end. This moment is delicate because, in addition to choosing the right fish, care must be taken in the method of introducing them to the tank.

Introducing too many fish at once would lead to a rapid increase in pollution, a spike in nitrites, and the death of some fish, at best. Depending on the fish and tank volume, it is advisable to introduce the fish in small groups with a one-week interval between each group.

Next, there is the issue of water. In pet stores, most fish are typically kept in neutral water (pH 7.0, GH 12.0). Informed aquarists have tried to adapt the water to the chosen fish or vice versa, but there is a high chance that the water parameters in the future tank will differ from those in the store’s tank. Therefore, the new fish need to be gradually acclimated to the new water conditions. Consider the temperature of the tank (let the sealed bag float in the tank), and the pH and GH parameters (use a drip acclimation system to gradually add tank water to the bag). The longer the acclimation period, the better the chances of the fish adapting to the new tank.

Once the fish are acclimated, they can be added to the tank (never pour the store’s water into the tank).

How to Start Your Aquarium Properly


The tank is planted, populated, decorated, and visually appealing—everything seems to be going well. Mission accomplished. Or almost. There’s still the matter of maintenance. Since the tank is a closed system, it’s necessary to regularly replace a portion of the water to replenish nutrients and remove accumulated waste.

The frequency and extent of water changes depend on the fish and the tank, but a good starting point is to consider changing 10% of the water every week. Under no circumstances should you exceed 40 to 50% per week, as such a drastic change could cause significant fluctuations in water parameters. Don’t forget to let the replacement water rest for an adequate amount of time to allow chlorine to evaporate and heavy metals to bind.

Regarding maintenance, trimming plants, removing debris, and fishing out any “UFOs” (Unidentified Floating Objects) should be done as frequently as possible. These actions will contribute to a stable tank and, most importantly, maintain a clean and pleasant environment for the aquarist.

mahatma gandhi portrait

- Mahatma Gandhi

“The greatness of a nation and its moral progress can be judged by the way its animals are treated.”

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