Fishkeeping 101: More than meets the eye

SINGAPORE – Keeping fish is often seen as an easy option, with a low barrier to entry, for first-time pet owners.

For parents, it is a gentle way to introduce children to caring for a pet. For working adults, a well-designed aquarium offers a calming visual escape at the end of a long day. 

Walk into any aquarium shop and the options would bedazzle you – guppies, platys and tetras come in a wide range of colours and patterns. 

However, while fishkeeping may seem convenient, it is not as straightforward as it seems.

Fish live entirely within the environment you create. Their health depends on the stability of the ecosystem and even small mistakes can have swift consequences. 

At first glance, maintenance seems minimal – feed the fish, clean the tank once a week and top up the water. In practice, a healthy aquarium requires consistency, observation and a basic understanding of how it all works. 

Environment matters: In and out

Start with the tank itself – its location matters. Placing it near an air-conditioning vent can cause temperature fluctuations, while direct sunlight leads to excessive algae growth. High-human traffic areas can also stress fish through constant movement and vibration.

Beyond its location, the equipment that supports the tank – filters, pumps, aerators and filter media – forms a miniature life support system.

These components regulate water flow, oxygen levels and waste breakdown. Before adding any fish, run the tank water for at least a week to allow beneficial bacteria to establish, a process known as “cycling”.

Tank size is another commonly misunderstood factor. Smaller tanks are actually harder to manage because water conditions change more quickly, while a larger tank provides greater stability. Even fighting fish and bettas, often kept in small containers, thrive in more spacious, well-planted environments. 

Water quality is the single most important factor in fish health. Regular testing for ammonia, nitrites, nitrates and pH levels helps prevent invisible imbalances from becoming deadly. Maintaining this quality requires consistent care.

Partial water changes – about 20 per cent of the tank – should be carried out weekly or fortnightly to remove waste and replenish essential minerals. Basic cleaning and upkeep of the filters would typically be done then. More thorough cleaning of equipment can be done monthly. 

Tap water in Singapore is safe to drink, but it is harmful to fish as it contains chloramine. It must be treated before use, either by ageing the water with aeration or by adding a dechlorinating solution.

Rainwater, too, may be unsuitable without treatment, as it can be too acidic. Care should be taken not to remove beneficial bacteria, which are essential to the tank’s ecosystem.

More than simply feeding fish

Observation plays a crucial role in fishkeeping. Feeding time, in particular, reveals a lot about your fish through their behaviour.

A good rule of thumb is to offer only as much food as they can consume within a few minutes. If they are still actively searching, a small second feeding can be given.

Any uneaten food should be removed shortly after to avoid polluting the water. Smaller, more frequent feedings are generally better than a single heavy one.

This attention to feeding matters because fish live in the same water as their waste. Uneaten food, waste and even the occasional dead tankmate can decompose quickly in warm conditions, rapidly degrading water quality.

A quick check of the tank at least twice a day to remove waste material can prevent small issues from escalating.

Regular observation is especially important to manage fish health. Fish illness can be difficult to diagnose and often progresses quickly. Prevention is key. Good water quality and careful monitoring will help you spot early warning signs.

If problems arise, it is best to seek advice from experienced aquarists and veterinarians. In some cases, gentler treatments such as salt baths or compounds like potassium permanganate or acriflavine may be used for freshwater species.

Fish species and their special needs

Choosing the right fish also requires care. While a mixed-species aquarium may look appealing, not all fish are compatible. Some are aggressive, while others are easily stressed or require different water conditions. 

Many species also have more specific needs – for example, some freshwater shrimp require cooler water and may need a chiller to thrive. 

Providing hiding places, such as aquatic plants or decorative structures, helps reduce conflict. It is also recommended to quarantine new fish for at least two weeks before introducing them to an existing tank to prevent the introduction of disease.

Resist the urge to stock many fish in one tank – excessively crowded tanks may lead to aggression between tankmates, even when they are of the same species.   

Fishkeeping may appear effortless, but it rewards those who approach it with patience and attention to detail. When done well, an aquarium transforms into a living ecosystem, one which is entirely dependent on you.