How to Save a Dying Fish After Water Change: Practical Solutions

Can fish survive a water shock?

Yes, if you act swiftly.

The most common case of shock is during and soon after regular maintenance.

Regular water change is a must, particularly for new aquariums that are yet to reach some form of equilibrium. But replacing 30%-50% of the water has its risks, especially when using tap water. Establishing a strong water-change protocol and following it diligently is the best way to avoid nasty surprises.

The most common reasons for fish entering a state of severe shock after water change are:

  • Temperature change
  • pH change
  • Chlorine
  • Ammonia spike
  • Osmotic shock

Here are the most common shock symptoms:

CauseWater Too ColdWater Too HotpH change
SymptomsLethargyErratic breathingLethargy
Lying at the bottomDarting aroundWhitening
ComaThrashingNo appetite
ComaErratic breathing

To learn more about how to prevent shock during maintenance, check out this detailed guide.

Keep in mind that fish can experience shock some time after the water change, especially if it’s been a large one and especially if you’ve washed the filters too. Canister filters and powerheads usually pack sponges or another form of bioactive filtration. Washing such colonies too aggressively will decrease their populations and can lead to fluctuations in the water parameters. Even if they aren’t aggressive and observable enough, they can have a lasting detrimental impact on the fish’s health. 

Now, let’s see how to save a dying fish from shock after a water change.

1. Check Water Parameters

If you see some of the above symptoms or other unusual behavior, check the water parameters. See whether the temperature is right, the pH and ammonia levels, and nitrites. During water change, the most common issues are pH and temperature fluctuations. They can send fish reeling, but, luckily, they are relatively easy to correct.

If a fish is acting weirdly after a water change, the fastest way to help it is to put it in a smaller vessel. The parameters of a small body of water can be altered much more easily, without affecting the rest of the tankmate.

A quarantine tank, a large jar, or a bucket with water from the aquarium will do the job. Fill it and adjust the water parameters as needed. Warm it up or cool it off with ice cubes. If you need ice, melt it before you place the fish inside. Close contact with it can cause a cold temperature shock.

In case the fish is suffering from a pH shock, adjust the water with a pH conditioner.

If the entire population of your tank is going through a temperature shock, you could increase the temperature by boiling a few liters of water. Conversely, too cool things off quickly, a strong fan or AC pointed at the water’s surface will do. Dissolving ice cubes and pouring very cold water can help too, but do it relatively slowly to not overdo it.

Naturally, the best thing to do is to check the parameters of the new water before putting it in your tank.

2. Increase Aeration

One of the side effects of a warmer water column is reduced oxygen levels. Ammonia buildup can also cause suffocation, as it begins to burn the fish gills.

To boost both overall aeration (i.e., better water flow) and oxygenation, increase the power of your filter. Changing its location can help in that regard. Adding an air stone will add oxygen as well.

In case the filter breaks down or there is an extensive period without power, you can help your fish manually. Grab a clean cup, fill it up with aquarium water, and then pour it back in from some distance.

It is simple but effective because the water surface is a place for active gas exchange. Creating waves increases its surface manifold, boosting oxygen absorption. And the artificial waterfall simply “inserts” oxygen into the water column.

Keep in mind that a larger water surface area is conducive to a larger gas exchange. In case of a filter or aeration system failure, aquariums with a larger volume of water (more gases in the water) and larger surface areas will last longer.

3. Check for Ammonia and Nitrites

Checking the ammonia and nitrites levels before and after maintenance is a good practice. It is best to do these checks a couple of hours after the water change, especially if you’ve trimmed water plants and washed filters. Both contribute to ammonia dissolution 

Naturally, if your fish is reeling, gasping for air, swimming erratically, or laying on the bottom, do a test immediately.

The fastest way to help it is to reduce the nitrite or ammonia levels with a water conditioner. Add it generously.

Ideally, the water conditioner will be capable of removing chlorine as well. High levels of chlorine will outright poison your fish.

4. Aquarium Salt Could Help

Aquarium salts are good for curing diseases and boosting fish’s immune systems. If all measures outlined above bring no results, add salt to the water. Salt — pure salt, not iodized table variation that can spike ammonia — will prevent the nitrite molecules from binding with their hemoglobin.

And even though salt reduces the levels of oxygen in the water column, it helps fish breathe better and more easily. If your aeration system is working properly, the reduced O2 levels won’t matter much, but the nitrite blocking will.

Salt is a good general cure too, for a number of diseases as it boosts the immune system and stops parasites from multiplying.

5. Don’t Feed the Fish

When something’s wrong with the water parameters, don’t give food to the fish. Food, for all its benefits, pollutes the water and can tip the scale in Anubis’s favor.

How to Prevent Shock in Fish During Water Change

A couple of strategies will help you prevent nasty surprises during water changes.

For starters, change 20% of the water instead of 50%. The smaller the volume, the less likely it is to affect the livestock in your tank drastically. Yes, it may call for more frequent maintenance sessions, but the risk is lower.

Have you heard of Osmotic shock? Osmotic shock occurs when the fish is thrown into radically different water, with wildly different chemistry. The very cells of the poor creature can burst. While this is unlikely to happen, introducing less new water removes the possibility altogether.

The second strategy concerns the maintenance procedure itself. Develop a routine for changing water and follow it strictly. The same steps and the same order every time. This way you are much less likely to forget something along the way.

The water maintenance routine should include testing of the new water for pH, temperature, and ammonia (at least). Periodically, most water suppliers perform maintenance of their systems and flush the canalization. I’ll spare you the details, but these procedures may alter the chemistry of your tap water too much for your fish to bear.

Test your water. Use a good gravel vacuum. Don’t rush things.

Take your time and enjoy the process. Fish are awesome pets but interaction is not their strongest suit. Cleaning their home is a very hands-on activity, and it is quite rewarding.

Also, if possible, I’d recommend not filling up the tank with tap water directly. Fluctuations in the water pressure could change its temperature and the fish won’t like this. For topping up the tank it’s fine, but for a major water change, it is a bit risky.

As long as you take the necessary precautions, fish won’t get overly stressed when you change their water. Moving things around will agitate them, but with the right process in place serious damage should be avoided.

Similar Posts

Leave a Reply

Your email address will not be published. Required fields are marked *