Fish keeping for beginners
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Fish keeping for beginners

Aquarium size

The recommended aquarium size will not only depend on the size of your fishes, but also on their temperament and sensitivity to change and high levels of nitrogenous waste. Keeping the water quality up (i.e. the levels of nitrogenous waste) down is much easier in a big aquarium than in a small one, since a large body of water will dilute the waste products produced by your fish. A big aquarium is also more resilient to rapid changes in temperature and water chemistry. As a beginner aquarist, it is therefore best to purchase a medium sized aquarium instead of a small one. If your budget forces you to choose between a small aquarium with expensive fish and a medium sized aquarium with inexpensive fish, you should definitely go for the later alternative. What use are expensive, flamboyant fishes when they float around belly up in the aquarium? As you grow more experienced, you can start buying more pricy fish species. As a beginner aquarist you should also refrain from aggressive fish species and fish species that are very delicate. Go for sturdy and peaceful fish and you will increase your chances of successfully keeping a well functioning aquarium dramatically.

Water movements

Water movements will force water from the lower reaches up to the surface, thereby ensuring proper gas exchange. The ripple effect on the surface will make the air exchange even more powerful. Without water movement, the levels of oxygen can become really low while the amount of carbon dioxide can reach unhealthy levels. Today, you can get a mechanical filter with an air pump that will create water movement while simultaneously filtering the water. You can also choose to add air stones to your aquarium. These are the two most commonly used methods among beginner aquarists.


The recommended water temperature will depend on which fish species you choose. It is therefore always a good idea to research your species before you bring them home. Generally speaking, fish will do best if you manage to keep the water temperature stable in the aquarium. Some fish species are amazingly adept at coping with change, but if you keep tropical species, most of them will be highly stressed if exposed to constant fluctuations in water temperature. A stable heater combined with a thermostat and an independent thermometer is therefore recommended. The wattage of the heater will depend on the size of your aquarium and the surrounding air temperature.


The biological clock of most fish species is regulated by the light and they will therefore do best in an aquarium where the onset of dusk and dawn takes place at predictable hours. Tropical fish species are used to roughly 12 hours of light per day, year round. Fish species living closer to the poles are used to long summer days and short winter days. The easiest way of providing your fish with a stable rhythm of light and darkness is to connect the aquarium lights to a timer.

Fluorescent lights are a better choice than incandescent lights since incandescent lights emit a lot of heat. This is not only a problem for your fish; it is a problem for your electricity bill as well since they consume much more electricity than fluorescent lights.

Biological filtration

The necessity of working biological filtration is often overlooked by beginner aquarists since they want to fill their aquarium with fish as soon as they have brought the tank home. Letting the water rest for 24 hours and then tossing several dozens of fish into it may work in some cases, but a lot of problems with sudden fish death is caused by this irresponsible way of handling living creatures. If you want to keep your fish alive in the long run, you should devote some time to proper cycling of the aquarium before you start to fill it. Cycling is the process where you allow colonies of beneficial bacteria to grow large enough to carry out powerful biological filtration in the aquarium. These bacteria will then continuously help you keep the water quality up in the aquarium. You can read more about how to cycle the aquarium by downloading the Tropical Fish e-book from the forum at AC Tropical Fish. (Downloading the e-book is completely free of charge.)

Aquatic plants

Fish love to hide among plants and even fish that hails from biotopes where plants are scarce can appreciate the hiding spots provided by lush plant growth. Keeping live aquatic plants is really easy as long as you stick to sturdy, adaptable species that will thrive even under normal aquarium lights and live on the carbon dioxide and waste products produced by your fish. By using live plants instead of artificial ones, you will provide your fish with extra oxygen during the day, since oxygen is a byproduct of photosynthesis. Live plants will also use waste products as fertilizers: thereby turning the waste into plant matter. This way, waste products will be removed from the water where they would otherwise decrease the water quality. If you have plant eating fish species, go for robust and fast growing plant species that will tolerate some nibbling and keep your fish well fed. There are however instances where the fish still destroys the plants completely and in such situations artificial plants can be a good alternative. If your fish destroys the plants by uprooting them, you can use floating live plants or live plants that can be anchored to stones and rocks instead of being planted in the substrate.

Choosing fish species

If this is your first aquarium, choosing sturdy and adaptable fish species is strongly recommended. As you gain more experience, you can start keeping more delicate fish species with taxing requirements. When you have decided on a bunch of species that you are interested in, do some research to find out their requirements, maximal size and if they would be compatible with each other. During the abovementioned cycling process, you should start by adding just a small amount of sturdy fish. A small group of the schooling Danios is one example of an excellent choice. When the water quality has stabilized you can proceed by gradually adding more and more fish over the course of several weeks.

Choosing fish specimens

Only buy fish from reputable breeders and well-kept pet shops. Avoid fish that show any visible signs of disease or distress, e.g. frayed fins, white spots, sore or discolored patches of skin, tiny worms that are attached to them, and so on. Ideally visit the pet shop around feeding time to see if the fish you are interested in have a healthy appetite. If a fish has arrived to the pet shop recently, you may have to tolerate clamped fines, dampened colors and a shy behavior since this is a normal reaction to being transported and introduced to a new home, but if the fish has been in the pet shop for several weeks and still hasn’t settled in, you should ideally refrain from buying it. Aquarium shops that allow dead fish to float around the aquarium or fails to quarantine diseased specimens should naturally be avoided completely.

Feeding fish

Research your fish species to find out which type of food they prefer and provide them with a varied diet. If you go for common beginner species, a high-quality flake food will normally serve as a good base. You can then start to experiment a little by culturing your own fruit flies or similar at home. Anyone who has lifted up a brown banana from a fruit basket knows how to cultivate fruit flies. If you keep bottom dwelling species, flake food is not a good idea since most of it will be consumed by other fish before it reaches the bottom. Get sinking pellets or similar to accommodate for the needs of your bottom dwellers. It is also important never to assume that algae-eaters will obtain sufficient amounts of food by grazing the algae in your aquarium – provide them with vegetable based foods as well.  

Feed your fish a few times a day instead of only once a day, and never give them more than what they can consume within 5 minutes. Left over food will rapidly foul the water and the excess nutrients can also cause an algae bloom. If you need to go away for a few days, your fish will cope without any food. Giving your fish extra food before you leave will only foul the water, which is especially dangerous when you are not around to carry out water changes.

Water changes

Despite how strong your biological, mechanical and chemical filtration is, and regardless of how many plants you cram into the aquarium, you will still need to carry out water changes on a regular basis. An aquarium can never become a perfectly balanced ecosystem since we constantly bring in new nutrients by feeding our fish. If you choose sturdy beginner species, changing 30% to 50% of the water once a week is a good rule of thumb. It might be a little messy at first, but you will soon learn how to do it fast and with a minimal amount of spill. If you change 50% of the water in your aquarium every week your aquatic world will be much more tolerant to common beginner mistakes such as over feeding. If you have chlorinated tap water, you need to use a dechlorinator or allow the water to sit in a bucket until all the chlorine has evaporated.

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