The Fish Guru

Avoid These Common Mistakes When Keeping Aquarium Fish

Aquarium fish are a popular and rewarding pet to keep. However, as with any animal, they require attentive care to maintain their health and well-being.

Unfortunately, many aquarium fish owners experience the unfortunate situation of having their fish die prematurely. These incidents can often be prevented by understanding the common causes of fish deaths and implementing preventative measures, which we’ll discuss in this article.

Poor Water Quality and Unsuitable Water Parameters

Perhaps the primary cause of aquarium fish deaths is poor water quality. A common issue is the presence of ammonia, which is a toxic substance created by fish waste, uneaten food, and decaying plant matter.

Over time, ammonia levels can spike, leading to ammonia poisoning in fish. Nitrites and nitrates also contribute to poor water quality, which can cause fish to become ill.

To prevent poor water quality, use a water testing kit to measure levels of ammonia, nitrites, nitrates, pH, and other parameters. Any abnormal results should be addressed promptly by changing some of the aquarium’s water and improving filtration.

It’s important to establish a healthy biological filter that can convert ammonia and nitrite into nitrates. Remember to regularly change the water and clean the filter to keep the aquarium healthy.

Poor Tank Conditions

The conditions inside the aquarium can be another factor that may lead to fish deaths. New tank syndrome is a common issue with new aquariums, as bacteria haven’t had enough time to develop to create a healthy environment for the fish.

Cycling is the process of building up the natural bacteria in the tank, which can take weeks or even months. Cycling the tank before adding fish is crucial to the health of the fish.

Another risk factor is persistent species that may require specific environmental conditions. Ensure that the fish you keep are compatible and can coexist in harmony.

Overcrowding, too many plants or decorations, and inadequate lighting can create stressful tank conditions that can lead to fish deaths. Aquarium lights should be limited to 12 hours per day, and wave makers should be turned off at night to prevent stress.

No Fish Acclimation

It’s essential to acclimate new fish into their environment, allowing them to adapt from pet store water to home aquarium water conditions. Acclimation means gradually introducing your fish to their new environment, so they can adjust to the temperature, pH, salinity, nitrates, and magnesium levels present in your aquarium.

This process can help reduce stress and minimize shock, caused by abrupt changes in the environment. This process can take anywhere from 30 minutes to several hours or even a whole day.

Fish should be placed into a plastic bag or container, and water from the aquarium should be added to the bag in increments over time. This will enable the fish to get accustomed to the aquarium’s environmental conditions.

Once the acclimation process is complete, the fish can be released into the aquarium.

Low Maintenance

Keeping an aquarium requires some maintenance. Without adequate care, water can become cloudy, stress levels can rise, bacteria can grow, and fish can become ill.

Maintenance includes performing water changes, vacuuming gravel, cleaning filters and dechlorination of water, avoiding detergent use near the aquarium, and frequent monitoring of the water quality. A healthy aquarium also requires appropriate feeding habits and a scheduled cleaning routine.

Wrong Fish Ecosystem

Each fish species has unique requirements for living comfortably. Some fish will be aggressive and will not coexist in harmony, while others may need specific food or shelter to thrive.

It’s crucial to research each fish species, considering factors like temperature, water hardness, dietary preferences, compatibility, and aggression levels before purchasing and adding it to the aquarium. It’s best to aim for a community of fish who will coexist harmoniously, thus reducing stress.


Fish are prone to various diseases that cause death if left untreated. Parasites such as Ich, bad bacteria, and ammonia poisoning, nitrite poisoning, and bacterial or fungal infections.

Fin rot can also be attributed to poor water and nutrition conditions, so ensuring a clean environment with appropriate levels of nitrate, ammonia, and pH, managing feeding habits, and reducing stress can prevent diseases. You should consult a fish disease guide if you suspect that your fish is unwell.

No Quarantine

It’s always good practice to quarantine new fish, allowing adequate time to observe, diagnose, and treat any problems before introducing them to the main aquarium tank. This process can last up to 4-6 weeks, allowing for adequate observation and diagnosis should any problems arise.

You can do this in a separate aquarium tank with similar conditions to prevent any contamination with current fish.

Old Age

The life expectancy of fish varies depending on the species. Some fish can live for many years, while others last only for a few months.

Signs of aging are common in fish, such as breathing problems, changes in appetite, and weak swimming patterns. These signs may indicate various issues, but old age is still a common cause.

Ensure that the fish receive appropriate nutrition and are kept in optimal living conditions.

Poor Feeding Habits

Overfeeding can lead to uneaten food, which can rot and pollute the water, leading to poor water conditions and disease. Uneaten food can also cause fatty liver disease, which can lead to the fish’s untimely death.

Introduce and measure food in the right amounts based on the fish size and dietary recommendations. Avoid feeding fish on an irregular cycle, which can lead to stress.

Toxins from External Sources

Toxins can come from external sources such as cleaning chemicals, unclean hands, or other contaminants. Be sure to wash your hands and avoid cleaning near the aquarium, ensuring that detergents, soaps, and other chemicals are not used near the aquarium.

Using a lid will also prevent possible pollutants from getting inside the aquarium.

No Lids

Aquarium lids serve many purposes, and not having one is a common mistake amongst beginners. Without a lid, water evaporates quickly, and fish may jump out.

Insects and other pollutants can also find their way into the tank if it’s left open. Prevent any possible mess by investing in an aquarium lid.

Agitation During Transport and Certain Movement

Fish need to be handled carefully during transport to prevent injury or death. Sudden movements or agitation can cause stress, leading to death.

Ensure that the fish are transported in a protective container or bag and are held gently. Also, ensure that the water temperature in the container is consistent with the one in the aquarium to avoid shock.


Stressful conditions in the aquarium can cause fish to become more susceptible to illness or disease, resulting in their untimely death. Factors that can cause stress include unstable water quality, temperature fluctuations, poor nutrition and feeding habits, aggression, bullying, and inadequate hiding places.

It’s essential to ensure your fish are kept in optimal living conditions to prevent stress.

Prior Problems with the Fish

Some fish may have pre-existing health conditions from the beginning or may have been unhealthy from the time of purchase. Always choose healthy fish from reputable sources and observe them carefully after purchase.

Congenital problems and bad stock can cause death even under optimal conditions.

Prevention and Solutions

To prevent the above issues, follow the below:

– Test your water regularly and monitor the levels of ammonia, nitrites, nitrates, pH, and other parameters

– Proper Aquarium Maintenance

– Fish Acclimation Process

– Suitable Fish Ecosystem

– Disease Prevention and Treatment

– Proper Feeding Habits

– External Toxin Prevention

– Reduced

Stress on Fish

– Conscious Fish Selection


Many factors can contribute to fish dying in aquariums, including poor water quality, ill-suited tank conditions, improper acclimation, insufficient maintenance, stress, and diseases. However, most fish deaths can be prevented by taking appropriate actions such as ensuring water quality and conditions, reducing stress, getting appropriate nutrition, obtaining proper acclimation, fish selection, and taking adequate precautions.

The success of owning an aquarium depends on how well it’s maintained and cared for and how well one can provide a suitable living environment for the fish. Aquarium keeping is an exciting and rewarding hobby that can bring immense joy and happiness to both beginners and experienced hobbyists.

However, it’s not without its challenges, and even experienced enthusiasts can make mistakes that can lead to disastrous consequences. In this article, we’ll focus on the common mistakes made by aquarium hobbyists and how we can learn from them.

Common Mistakes in the Aquarium Hobbyist Journey

Regardless of the level of experience, there are common mistakes that aquarium hobbyists make. Here are a few:

Human Error: No matter how cautious we are, human error can still occur.

It’s common to forget to replace water, skip maintenance tasks, or even forget to turn off a power filter, creating unsuitable conditions for the fish. These mistakes can lead to stress, disease, or even death.

Beginner Mistakes: Beginners are more likely to make mistakes that an experienced hobbyist wouldn’t make. For example, adding too many fish, not cycling the tank correctly, buying unsuitable fish, or not checking the water parameters before adding fish.

Expert Mistakes:

An experienced hobbyist can still make mistakes that may lead to undesirable results. They can also be overconfident in their knowledge base.

For example, assuming that a fish can thrive under certain conditions or leaving the decision of acclimation process to the supplier. Failure to Learn and Improve: Every mistake is an opportunity to learn and improve.

It’s crucial to acknowledge when a mistake has been made, take corrective action to prevent recurrence, and seek advice if necessary. Ignoring mistakes or failing to learn from them is a considerable risk to the hobbyist and the well-being of the fish.

Learning from Mistakes

Making mistakes is inevitable, but it’s essential to learn from them to avoid repeat mistakes, promote growth, and improve skills. Here are ways to learn from mistakes:

Experience: Experience is an excellent teacher.

With time, hobbyists will naturally learn from their mistakes and gain the expertise required to maintain a healthy and thriving aquarium. Research: Research is essential for success in aquarium keeping.

By doing research, hobbyists can prevent mistakes from occurring, learn from the experience of others, and get insights from blogs, forums, and expert guides. Communication and sharing: Aquarium enthusiasts can learn by sharing their experiences and mistakes with others.

Sharing and communicating will allow hobbyists to learn from each other, avoid mistakes, and promote better care of the aquatic community and their enshrined pets.

Improvement: Correcting and preventing errors requires continuous improvement, and taking corrective action is crucial to growth.

By improving knowledge, skills, and habits, hobbyists can avoid previous mistakes, improve the aquarium environment, and build healthy relationships between them and their aquatic pets.


The aquarium hobby is both a rewarding and challenging endeavor that can provide hours of enjoyment. Mistakes can happen to anyone, but the key is to learn and grow from those mistakes.

Experienced hobbyists and beginners alike should acknowledge their mistakes, learn from them, and improve their skills continuously. Above all, it’s crucial to maintain healthy and thriving environments for aquatic pets, promote growth and learning, and continue to enjoy the aquarium hobby.

In conclusion, aquarium keeping is a fulfilling hobby that requires attentive care to maintain healthy and thriving environments for aquatic pets. Common mistakes in the hobby include human error, beginner mistakes, and even expert mishaps.

Learning from these errors is crucial, and may involve gaining experience, researching, communication, sharing, and continuous improvement. By minimizing these blunders, we can enjoy and promote the aquarium hobby to the fullest extent while providing the best conditions for our aquatic pets.

The takeaway message is to be mindful, learn from mistakes, and take the necessary steps to ensure a healthy and rewarding experience for ourselves and our aquatic friends.

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