Guides on How to Add Fish to Tanks

Adding fish to your tank can be a technical task. You need to consider fish compatibility, quarantine fish before introducing them, acclimatize fish to tank environment, etc. In this guide, we will cover how to add fish to fish tanks, including introducing fish to new tanks and adding new fish to old tanks.

How long does it take to cycle the tank before adding fish

When adding fish to your tank, cycling the tank is an essential part. Cycling means the process of establishing beneficial bacteria. As the cycling progresses, nitrite levels will gradually decline, and nitrate levels will start to rise. The cycling process is considered complete when both ammonia and nitrite levels consistently read zero, and nitrate levels are present.

Generally, the nitrogen cycle takes several weeks (about 6 weeks). Without a great nitrogen cycle, some issues would appear in your tank, which is harmful to your fish. For example, the New Tank Syndrome and nitrite poisoning.

Introducing fish to a new tank

Preparing and cycling tanks before introducing fish

Before introducing fish (new or old fish), some preparation is necessary. The first key point is setting up a new tank. During this process, you should not add aquarium decorations with sharp edges, which will cause fish injury. Also, when decorating your tank, fish requirements for tank conditions should be taken into consideration.

After that, one of the vital steps is cycling your new tank. Commonly, cycling new freshwater tanks takes at least 4–8 weeks, while new saltwater tank cycling needs at least 6 weeks. After cycling, it is necessary to monitor water quality to prevent New Tank Syndrome. By the way, some fish are best for starting up a new tank. Take saltwater tanks as an example, Damselfish is a great addition to a new saltwater tank.
add cichlid fish to tank

How to introduce fish to a new tank

Once cycling is finished, you can introduce fish to a new tank. Next, let’s take a look at how to introduce fish to new tanks, including old fish and new fish.

  • How to introduce old fish to a new tank

First, you can siphon the water in the old tank into a clean container and then stock old fish in the container temporarily. If everything is ready, it is time to introduce the old fish to the new tank. Just move the fish from the temporary container to the new tank with a fish net. After transferring, you should pay attention to the fish and aquarium status. If anything is abnormal, you should find causes immediately and then take measures to tackle the issue.

  • How to introduce new fish to a new tank

Stock new fish in a container with partial water from the new tank, and then wait for about 30–45 minutes. After 30–45 minutes, turn off the aquarium light and provide a stress-free aquarium environment. Then you can introduce over one fish once. Just add the fish to the new tank with a fish net.

Adding new fish to old aquarium

Quarantine new fish

Before introducing, quarantining the new fish is of the essence. Generally, it should last about 2 weeks, which allows you to check whether new fish suffer disease or not, and decrease the risk of disease infection.

During the quarantine period, closely observe the new fish for any signs of abnormal behavior (e.g. loss of appetite or physical injuries) and visible symptoms of diseases, like fin rot, ich, or parasites. Also, to ensure optimal conditions, you should check water parameters regularly, such as temperature, pH, and ammonia levels. Commonly, it is feasible to add new fish to the old aquarium after the quarantine period.

Check and adjust the old aquarium (established aquarium)

  • Test water parameters

Check whether the water conditions are within ideal ranges or not. If there is ammonia or chlorine in the tank, correspondingly, you should treat the water with the help of an ammonia binder or a de-chlorinator.
add guppy fish to new tank

  • Do water changes

Changing 25-30 percent of water is great. It provides better living conditions for new fish and is beneficial for new fish growth. During the water change process, a water changer will help you a lot. It can change water quickly, enabling you to drain or fill the tank with water more easily.

Acclimatize and add new fish to the old aquarium

Stock the new fish in a container with partial water from the established aquarium for about half an hour. If everything is great, you can add the new fish to the old aquarium with the help of a fish net.

After that, it is best to turn off the aquarium light for a few hours. Then fish can adjust to the tank environment gradually. Furthermore, it is feasible to add some food to distract the fish and reduce the stress on new fish after one hour.

In summary

To conclude, there are differences between introducing fish to new tanks and adding new fish to old tanks. If you want to learn more about adding aquarium fish to the tank, you can go to How to Add Aquarium Fish to the Tank.

That is all for today’s guide. If you have more ideas about adding fish to tanks, welcome to share with hygger in the comment. We are happy to receive your sharing. Finally, thanks for your time. Wish you a pleasant experience in the aquarium.

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