How to Tell if Fish Are Happy in New Tank? – 7 Signs

how to tell if fish are happy in new tank

Have you ever wondered “how to detect if fish are happy in new tank” and cannot find any relevant information for that? Trust me, this post is for you.

Since it is hard to detect your pet fish’s emotions as compared to other species, you should watch their reactions to external factors. For example, their interactions with other tank mates or their colors all provide you with the insight you want.

No more beating around the bush, scroll down and receive more tips on how to tell if fish are happy in new tank!

Signs to Know if the Fish is Happy in the New Tank

To tell if the fish enjoy their new lives or not, you should start observing them from the most general things to the more detailed ones. As it might be confusing, this list will surely clear things out.

1. Interactions And Behaviors


First things first, your fish’s casual interaction and friendly behavior toward the other members in the tank are critical whenever you want them to fit in a community tank with different species.

In case your new fish is getting along with its housemates, you will see it swimming joyfully and acting lively.

On the other hand, your fish tries to hide in the tank corner, refuses to engage with the others, or is extra sensitive/aggressive; maybe your “mix-and-match” is wrong.

Watch out, once you unintentionally put a well-behaved fish into a tank with territorial ones, they might be bullied, stressed, or even die.

To illustrate, never let betta fish stay with other aggressive species. They are territorial pet fish that are known for being dominant and aggressive.

2. Swimming

As I mentioned earlier, seeing your fish swimming fast back and forth or showing off their energy means your pet is doing well here.

Yet, don’t expect your beloved pet to react positively right after you introduce it to a new home. It might be shy for a while before starting to merge with the whole aquarium’s vibe.

However, in case the fish swims up and down randomly rather than back and forth, they might undergo stress or have some kinds of parasitic infection. Be conscious!

3. Breeding


Fish only produce their next generation once they feel satisfied, safe, and secure with their living area. Depending on the fish’s nature, they act differently in order to attract their partners.

With some specific types, the males will try to tempt the chosen females by physical contact, which might be distinguished from the other species.

Male goldfish, for example, will commonly bump the female’s belly to signify that he is ready to spawn. Betta fish, on the other hand, will begin to build bubble nets and seek partners.

4. Appetite

The next factor to take a look at is the appetite of your pet. Usually, stressed fish (or even the other species) refuse to eat. To check on this, you need to give them food with a fixed and stable routine before doing the observation and evaluation.

In rare cases, the food (smells, tastes, etc.) just does not appeal to your fish, and you may quickly rectify the situation by switching their menu.

On the other hand, the issue is that the living environment (pH level, temperature, or otherwise) is unstable, causing your fish to get agitated and stop eating.

5. Colors

The fish’s appearances are the easiest and the most significant signal for even the novices to know more about the condition or emotion of their pet. About the colors, you should ensure that your fish is having their expected hue, which is not too dark or too light.

A blue fish, for instance, with its perfectly lovely, dazzling hue, is a happy and healthy fish. In comparison, if you see any paler or darker tones than usual, it’s time to address the issue straight away.

Based on my observations, the problems might be related to the ammonia level or their menus, so beginning with them will probably work.

6. The Wholesome Fins


Fins are essential parts of these vulnerable species; which help to lift them while swimming and more. Therefore, the fin problems might be a signal for another dangerous disease, like fin rot or fin fungus.

Think positively, fish with ragged/ripped fins are only stressed out, feeling unhealthy, or being bit by their tank mates.

However, you should evaluate the situation and act quickly to save the sick fish and prevent the sickness from spreading to the other fish in the tank.

7. Breathe


Fish obtain oxygen directly from the water through their gills and mouths. As a result, you can identify if your fish is breathing properly or not by observing how fast these parts inflate abruptly or slowly, as well as the pet’s behavior when trying to ingest oxygen.

To begin, pay particular attention to your fish’s breathing rhythm. If the routine is really unstable and your beloved pets try to gain more oxygen by coming to the surface to gulp, you should think of the best approach to save them.

Normally, the “culprit” is the water quality, so you may start correcting it with this clue.

No more asking “how do I know my fish is happy in its new tank”, you can utilize all the recommended tips above from now on.

For more information, it might be harder to tell whether your ways to keep your fish happy in the tank or not relying on the proposed factors; yet, you can do your best to make their life easier. A good filter and a large-enough pond are the first-to-care-for.

Ways to Keep Your Fish Happy in the Tank


Aside from understanding the indications that suggest when your fish is sad or happy, you should also be aware of the techniques that may assist you in preventing troubles in the first place.

1. Don’t try to stuff things, fish, and decorations inside your tank

Too much of anything may lead to the opposite effect, and this is no exception. Your pet needs space to swim and freely explore, so do not overstock your aquarium.

Try to give each inch length of your fish at least 1 gallon of water and I’m sure they will thank you for that.

2. Clean your fish tank regularly and ensure that the living environment is clear enough

In order to do so, I highly suggest you clean your tank inside out once a month. Don’t skip any step here and refill the tank with pH-stabilized freshwater.

Remember to employ a good filtration system since it helps to filter out any unwanted contaminants or substances more efficiently.

3. Keep the water temperature stable as much as possible

Water temperature does affect your fish’s health and this factor depends on which kinds of fish you are raising. More detailedly, Endler’s Livebearer, Odessa Barb, or other chilly fish prefer cooler water while some kinds of warm water fish don’t like that condition.

Furthermore, water temperature also affects the reproduction and the appetite of your pets, which can directly harm them. Therefore, it’s a must to take care of this issue.

4. Spend a proper focus on the lighting system

Never forget to light your fish tank at least 12 hours a day because every living creature needs light to survive, not excluding fish and plants in your aquarium.

In this case, the lighting system will replace the sun to provide enough conditions for your plants to photosynthesize and produce more oxygen.

5. Watch the amount of food you provide them carefully

It’s difficult to tell when your fish are hungry because they are always in the mood to eat. Their nature makes them eat as much as possible in any occasion; however, fact tells that they will spit out the food after 3 or 5 minutes of devouring.

My advice for you here is to feed them twice a day only and ensure to provide them a small amount of food at one. Believe me, you won’t want to overfeeding them and unexpectedly make their living environment worse.

Making fish happy in tanks with my top suggestions will leave you with no signs of unhappy fish!

Frequently Asked Questions


How long does it take for fish to settle in a new tank?

Based on my experience, it’ll be around 1 hour for your fish to get used to the tank’s temperature and habitat. Don’t put the fish in the new tank straight away; instead, leave them in the bag (from the store) and soak them all in the tank water for the specified time period.

How can you tell if a fish is unhappy?

If fish in your tank appears in darker colors than before, hiding in the bottom all day long, rubbing the body against gravel frantically, or locking the fins, and refusing to swim and interact with the tank mates, it might be unhappy.

How do I know if my new fish is doing well?

Aside from the symptoms listed above (such as hunger, coloration, breeding, or fish interactions), each fish type can have distinct behaviors indicating that they are happy.

For example, when a goldfish is happy, it is exceedingly sparkly, swims continuously, feeds regularly, and, yes, creates feces constantly.

Why is my fish huddled in corner of tank?

It’s because your water temperature is now too cold for your fish. In contrast, if the water is pretty hot for them, they tend to “stick” to the bottom of the tank to find a cooler area.

From now on, once seeing your fish hide in tank, your first move should be checking the water temperature.


To summarize, the suggested indicators above are all applicable since I used them to make my fish happy before. From now on, don’t be worried if you notice your fish swimming back and forth in their new tank; start checking the tips and take any necessary action.

Do you have any further questions about “how to tell if fish are happy in new tank”? It would be my pleasure to hear and answer any future questions you may have, so please leave a comment below.