Saving a dying fish after a large water change is a challenge many fish tank owners face and needs careful attention. If you have experienced this and are finding reasons why this happens then before we move further it is necessary to understand that why fish die even if you took all the care and followed the correct procedures while water changes.
Sadly there are plenty of reasons why fish die after water changes, but the most important of all of them is “shock or stress”. If yours is a tropical fish tank then you have to be very careful “before” you plan a big water change. If you do not have the facility of storing water, before you add it to main tank then you can even start treating it with commercially available products that treat water to desired chemical properties.
Water when changed in big quantities, brings all sorts of new parameters into the existing settled ecosystem and these new parameters are responsible for the “shock” that fish cannot survive.
Many times you’ll see fish giving you behavioral signals that they are under stress and this is a clear indication that something went wrong during or before the water change that caused them to go in stress. That is why always observing fish behavior is a good habit as a fish tank owner. Lets’ have a look at one by one why fish get under stress after water changes.
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Why Are large water changes needed?
If you maintain your tank every week then you’ll not need large water changes often in your
tank. Large volume water changes are required in emergency situations such as ammonia and
nitrite level spikes beyond allowable limits. These can happen for several reasons such as
1) Failure of filter mechanism
2) Filter media clogged
3) You missed cleaning schedule
4) Dead fish not removed from the tank for prolonged time.
5) Instead of moving sick fish to quarantine tank, medication added to main tank
6) Lots of uneaten food settling at the bottom (because of sick fish not eating)
7) Suddenly adding new stock to fish tank (Too many fish in tank)
There are many more reasons why water chemistry can get disturbed and to avoid this you must own a water testing kit that keeps track of what’s happening with gas levels, so that you never have to change too much water in the first place.
Temperature raising or lowering too fast
When new water is being added to the fish tank for water changes, it is necessary that the new water has the same chemical properties as the older one. Though matching exact figures is almost impossible for anyone, it is necessary that they are close enough.
New water will have a lower temperature than the water that was removed and to solve this many fish tank owners will try to hurry to increase water temperature so that it matches the required levels. This can be a big mistake when it comes to tropical fish tanks.
Sudden changes or too fast temperature changes can result in “shock” and fish can die due to this. When you add new water let it settle and gradually allow temperature levels to increase to the required levels. Fish are extremely sensitive to sudden changes to anything in their environment and failure of careful attention to see smallest of factors can result in stress.
Water quality and chemistry
Water quality is the most important of all the deciding factors when it comes to saving fish from dying after water changes. Water quality is not just physical purity of the water but include dissolved gases and chemical non visible elements present in the water.
Though these are non visible to humans, fish can easily and immediately detect them and respond accordingly. While adding new water to the fish tank it is necessary it is chlorine free. To achieve this you can save it for at least 24 hours before you add it to main tank so that chlorine has disappeared from it. You can add commercially available products for chlorine removal as well.
Test water that is being added
The best way to ensure that water is safe for fish is to use a water testing kit and check levels of ammonia, nitrites and nitrates for safe levels. These tests are to be made before the water is being added to the main tank or even before you start to remove original chunk of water quantity.
Many times tap water available from the municipal water supply is never safe for fish tanks and needs to be treated in some or the other way. Tap water always contains chlorine which is harmful for most fish.
Any sudden changes in ammonia, nitrites, nitrates, pH of water will cause great deal of stress and fish will show changes in physical behavior. If not treated, fish can die.
Oxygen levels in newly added water
Apart from water chemistry, decreased oxygen levels in tank, is another big reason for fish dying after water changes. Once water is changed it is necessary that all the necessary equipment that takes care of the oxygen levels such as air pumps, bubbler, power heads or aquarium wave maker are in good condition and running so that exchange of gases starts immediately supply fresh oxygen in newly added water.
Observe fish behavior
When there is a large volume water change it is necessary that you closely observe how fish behave in the first few hours. Some of the things that you can observe could be related to behavioral changes and physical symptoms like these.
1) Clamped fins
2) Gasping for air at top (Read more)
3) Too violent
4) Lazy and lethargic
5) Hiding themselves
6) Rolling over and losing balance
7) Red gills
If you see any one of these signs happening then you can fairly assume that you are moving too fast when it comes to water changes. As mentioned above fish are extremely sensitive to environment and anything that puts them in stress is going to be a big trouble.
While water changes are a necessary part of the fish tank, learning this skill is even more important in the long run. Now there are some fish tank owners who can get along with no water changes at all, once the tank is set up, but this requires lots of knowledge and experience. If you are just new to this hobby then it’s always better to do partial water
changes and stay in safe zone.
Being safe after water changes
One of the best ways to be safe after small or big water changes is to make a check list of all the physical equipment that is attached to the tank is running or not. This may include.
1) Water heater for tropical tanks
2) Air pumps for aeration
3) Water filters
4) Bubbler, wave maker or power heads of you have them
5) Lighting if you have them.
AL these in combination work to maintain the desired environment that was there before the water changes. If you forget to turn any one of these on then there is going to be difference in chemistry in some ways and this can lead to stress or shock.
Method to completely avoid water changes
Many homeowners can achieve a 100% no water change tank, but requires lots of experience and knowledge of water chemistry and what really works. A lot of this is also dependent on how big you tank is. But for newcomers it is always recommended that to keep water chemistry intact, you do partial water changes once a week and be safe.
But there is a way to bypass water changes and still be on safer side. What you can do is keep the water flowing just like it is found in natural world. This can be done in the form of a drip feed system where fresh treated water enters from one end and excess water overflows outside from top that can be connected to a garden hose.
This drip feed doesn’t have to be in big volumes. Anything in between 1-2 gallons per hour for a 200 to 250 gallons tank will work perfectly fine provided you have a continuous water supply available in your home. The only precaution that’s necessary is the water that’s coming in has to match all the required chemical and temperature parameters if you have a tropical fish tank. However will work perfectly for a cold water tank and if set up
correctly you’ll need much less maintenance.