How to Avoid Stressing your Fish

There are many different things that can stress your fish. If the fish were in the wild, they wouldn't have to contend with many of the man made stressors that face them in an aquarium. So what are the stressors and what can we do to reduce the impact on our fish? Well read on my friend and we shall discover more...

Poor Water Quality

If the quality of your aquarium water is poor then your fish with without doubt suffer, and could die. Polluted water to a fish is like polluted air to a human. It is not enough to simply set up your tank and let it 'do its thing', you have to check the water quality and check the filter systems are working.

Your fish produces waste which drops to the bottom of the tank. When this happens and the filer is not sufficient, the pH of the water will drop, ammonia and other compounds increase. Carbon dioxide will build and the level of dissolved oxygen will fall sharply. When this happens the fish will become stressed.

If this is left unchecked the fish can become susceptible to pathogens or even die. You have to remember that a stressed fish has an increased heart rate and has to work harder to breathe. Checking and maintaining you filtration system can help avoid this situation. Other tips to avoid a decrease in water quality are to not over populate your tank and to regularly use water parameter tests.

Capture Stress

This form of stress to the fish is also known as 'handling stress.' Every time you catch a fish, chase it with a net or interfere with it, you are causing it stress. Whilst you may have the fishes best interests at heart, you are acting as the stressor to the fish. It sounds ridiculous to say, but this type of stress can be fatal to a fish.

You can reduce the amount of capture stress inflicted on your fish by reducing the amount of time that you transport a fish for. You should also not attempt to net a fish unless it is absolutely necessary. Furthermore, make sure that you use a net that is big enough for the fish you are trying to trap. A good indication that the stress is subsiding is if the fish starts to feed.


If you have too many fish in your aquarium then your fish can become stressed. Not only will this lead to a poor water quality, but there may be territorial disputes between the fish which could cause injury or death.

Temperature Fluctuations

The heater on your saltwater aquarium will work on a thermostat. If this fails to switch on or off then you are left with very cold fish or fish that are too hot. In reality the first you will know about this is when you find your fish have died.

However more subtitle changes in temperature will also affect your fish. For example, introducing new fish to your tank from a bag too quickly could cause the fish to stress. The golden rule is to check not only your heater, but your thermometer on a regular basis.

Salinity Fluctuations

As you will be aware, it is important to keep the level of salt in your table stable and at a level which suits your fish. If the level of salt in the water changes rapidly then your fish will suffer. This type of stress is called osmotic stress because it disrupts the osmotic balance of the fish.

If this balance is disrupted to a significant degree then the immune system of the fish may become compromised. You should check the level of salt in the aquarium on a regular basis. Remember something as simple as evaporation will affect salinity levels.