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How to prevent fish illness & stress


Would you be surprised if we told you that stress is one of the main causes of disease in your aquarium?

Just like humans, fish get can stressed by certain situations. This makes them run down and more likely to get sick and hide away, or even die.

To keep your fish healthy and prevent or solve stress it’s important to understand the causes.

The most common cause of stress is poor water quality.

Even if your water looks clear, it doesn’t mean it’s safe and healthy for your fish; the causes are invisible.

The main cause of poor water quality is a build-up of fish and plant waste. As these begin to rot and break-down they release toxic chemicals like ammonia, nitrite and nitrate and can change water pH levels. This toxic cocktail stresses your fish making them prone to disease.

A filter should help prevent this problem; the beneficial bacteria within the filter work hard to break down toxic chemicals.

But if you have a new, immature or badly-maintained filter, the toxins won’t breakdown quickly enough, and in some cases, may not break down at all. Watch this video to understand how this process works in your filter, or read on for more…  

Because water quality problems are invisible, the only way you can monitor them is with regular use of water test kits.

Like us, fish are constantly exposed to bacteria and viruses, but when healthy our immune system deal with these. Do what you can to give your fish a stress-free life; and they’ll fight off common diseases more easily.

Other common stress triggers for your fish - and how to deal with them - are:


Sustained changes in temperature will stress tropical fish.

Temperatures should not stay too high (above 29°c) or too low (below 21°c) for any amount of time.

A good heater will keep the temperature at a safe level (24-25°c) for most tropical species.

Quick changes in temperature can also upset your fish, so make sure you use a thermometer and match water temperatures when doing a water change and carefully acclimatise fish when adding them to a new tank.

Environmental stress
Physical stress
Other fish
Environmental pollution
Fish waste

Avoiding stress in your aquarium is the key to preventing disease, but some stressful situations just can’t be avoided.

If you know a situation is going to be stressful for your fish, you can help them cope by adding a tonic salt.  Read more about why tonic salts help your fish feel better.