Why Do We Acclimate Our Aquarium Fish?

Fish are hypersensitive to their surroundings and need to be gently introduced to their new home. If you bring your fish home and plop him directly into this new tank without acclimating him properly, he may experience any number of stressors causing severe trauma or even shock-induced death. It’s vital to check the basic parameters including temperature and pH before adding fish to their new aquarium.

Where to Begin the Acclimation Process

Acclimation - Step 1

Get your new tank ready and have water conditioners, a thermometer and testing supplies on hand.

There are a few different situations you may find yourself in. You might have set up an aquarium weeks ago and cycled it to prepare for your new fish. You may have a community tank already and have decided to quarantine your new fish for the suggested 4 week period before adding him to the group or you may have decided to do full 100% water changes and are setting up your aquarium just before the acclimation process. If you are setting up a new aquarium, it is suggested that you do it 24 hours prior to acclimating your new fish to allow for off-gassing.

The first step in the acclimation process is to test the water parameters in your fish’s bag or cup. Check and record the temperature and pH. You may also want to check for ammonia, nitrite, nitrate, GH and KH so you know what you’re starting with. After all, once you toss that old water, you will never get that information back. Temperature and pH, however, are the most critical. Test and record the temperature of the new tank. If the temperature in the bag varies from that in the tank, even by just a few degrees, you will want to float the bag (or betta cup) in the aquarium until the temperatures match. Before you float the betta fish container, test the bag/cup water’s pH level to determine if it is different from your aquarium’s pH.

Adjusting pH

Acclimation - Step 2

The most important water parameters to coordinate when acclimating your new betta are temperature and pH.

Bettas prefer soft water with an ideal pH between 6.0 – 7.0; however, they can adjust to a range of pH levels so long as they are consistent and not rising or falling quickly. If you find that your tank’s pH is different from the bag water, I suggest you take more time acclimating the fish rather then altering the pH with chemicals like pH UP or pH DOWN. Those chemicals tend to make quick drastic changes in the pH only to have them quickly and drastically revert back to where they were. Remember, those rapid fluctuations are more dangerous than a stable pH outside of the ideal range. To bring the pH levels closer, add a small amount of aquarium water to the bag/cup water every 5 to 10 minutes. If you are floating a standard betta cup like the one shown in our photo, adding just a couple of tablespoons of aquarium water through the hole in the lid throughout the acclimation process will help slowly adjust the pH level. API Freshwater PH Test Kit, 250 tests per Kit

Floating the Bag or Cup

Once you have your parameters checked and your water conditioned you are ready to float the bag or cup. If the bag and tank water parameters were already very close then usually 15 – 20 minutes will be sufficient. If the parameters differed, then longer may be necessary. If the pH or other parameters were off then I suggest taking more time to acclimate your betta – up to an hour or more. When the time is up you can slowly release the fish trying to avoid adding dirty bag water to the tank.

Acclimation is Stressful

Acclimation - Step 3

The amount of time needed to acclimate your new fish may vary from 15 minutes to an hour or more.

Remember, the acclimation process can be pretty stressful for even the hardiest of fish. Even stretching the process to an hour or two doesn’t really give the fish enough time to adjust properly. Be vigilant of your new fish and keep an eye out for signs of stress or disease, especially in the first two weeks after acclimation.

This is just one method for fish acclimation. If you have another, feel free to write in and we’ll share it with our readers.

The Drip Acclimation Method

Another popular fish acclimation method is the drip method, which utilizes two containers and a piece of airline tubing. This method is popular with fish keepers who keep more fragile species and is great for bettas too as it acclimates fish slowly and safely.

First you will need your aquarium and the container your fish is in (bag, cup, tupperware, etc) close by each other. You will be slowly adding water from your aquarium into your fish’s container so make sure there is plenty of room to add more water; at least the same amount of room left as there is water in the cup already.

Take a piece of airline tubing (the same plastic tube you attach to your airstone if you have one) that is long enough to reach from your aquarium to the container your betta is in. Tie a tight knot anywhere in the middle of the tube. Secure one end in the aquarium. Create a light suction on the other end so that the water slowly begins moving from the aquarium through the tube.

If sucking on the end of airline tube grosses you out (particularly if it has been in an aquarium before) you can make a tight fist around the end of the tube and suck through your hand. It takes very little effort to get the water flowing.

Acclimation - Step 4

The following weeks after acclimation are the most critical. Watch your new fish closely for signs of stress or disease.

Put the other end of the tube in the betta cup or bag. The water should drip slowly, at the rate of about one drop per second. If it is coming out too fast tie one or two more tight knots in the tube to adjust the flow rate.

Remember, you have created a siphon which is being fed by gravity. If your betta bag/cup sits higher than the surface of the water in your aquarium, the water will not flow.

Take as much time as necessary to match the betta’s water with the new aquarium water. You typically want at least 50% of the water in the betta cup to be from the aquarium.

Keep an eye on the water flow with this method so that you don’t overfill the betta cup.

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