Are Your Fish Happy? Here’s How to Tell 

Happy Fish in Fish Tank is the only Way Keep them Healthy Fishkeepu com

Owning an aquarium full of fish is a big responsibility, but your fish will surely bring you hours of delight and entertainment. It is only reasonable that you would want to make sure fish were as happy with you as you were with them. 

But are your fish happy? Fish are not complex emotional creatures and require little to make them happy. Your fish are happy if they are healthy and live in a stress-free environment. The signs of a happy fish include:


  • Swimming normally
  • Eating regularly
  • Breathing normally
  • Looks normal
  • Breeding
  • Behaving normally


So, if all is normal, your fish is happy! In this article, we will discuss more about how to tell if your fish is happy, why your fish might be stressed, and how you increase the happiness of your fish.

How to Tell if You Have Happy Fish

It can be hard to tell if your fish are unhappy. Their behavior isn’t as easy to read as a dog or a cat, which can be vocal and expressive when they are unhappy. If you’re a new fish owner, it can be even harder because you don’t know what normal fish behavior looks like.

The most obvious sign that your fish is happy is that it is acting as it normally does. Let’s go over them more in-depth so that you know what to look for.

Happy Fish Sign #1: Your Fish is Swimming Normally

Some people might claim that a happy fish will swim throughout the tank without taking cover, but this isn’t wholly true. Many fish will swim throughout their tank when they are happy, but there are some types of fish that prefer the bottom level of tanks and others that are happiest when they’re hiding.

Here are some of the types of swimming you should look out for:

  • Erratic, irregular, or frantic swimming or crashing into objects or glass. This can be a sign of stress or a health issue.
  • Unable to swim up or down. This is a classic sign of swim bladder disorder. There are several things you can do to help make your fish more comfortable if it has swim bladder disorder.
  • Swimming alone. Consistently swimming apart from other fish is only a problem if your fish normally likes to swim with others as a school.
  • Swimming at the bottom of the tank without coming up often. This is a sign of several health issues, poor tank conditions, and stress. Some types of fish are bottom dwellers, so make sure you do your research on your specific type of fish. ( Fish Lay On The Bottom of the Tank)

The important thing is that your fish is swimming and using the tank as it should. This is where researching your fish breed becomes important.

Happy Fish Sign #2: Your Fish is Eating Normally

A fish too stressed out, scared, or sick to come out of its hidey-hole will not swim to the top of the tank at feeding time. Most fish will happily swim to the top of the tank when they see the fish flakes appearing because if they don’t, there might not be anything left after the feed frenzy. 

In fact, fish will eat themselves sick in most cases, so if your fish isn’t eating, there is definitely something that matters.

Not only is not eating a sign that your fish isn’t happy or healthy but being hungry will only add to your fish’s misery.

However, it is important to note that some types of fish don’t swim to the top when they see fish flakes. For example, bottom feeders usually wait for the flakes to fall to the bottom or ignore them and stick to algae.

Happy Fish Sign #3: Your Fish is Breathing Normally

If your fish isn’t breathing as it normally does, this is a clear sign of a serious issue and an indicator that your fish isn’t happy.

Abnormal breathing can take different forms. Here’s what to look for:

  • Slowing down of the fish
  • Rapid gill movement
  • A fish that appears to be gasping
  • Fish coming to the top of the tank for air
  • Fish that hovers near the air pump

If your fish is exhibiting any of these signs, it is likely that the amount of oxygen in the tank is not optimal. Using an air pump and regularly changing out the water in a tank will help keep oxygen levels where they should be, but immediate action does need to be taken, or your fish could die of oxygen deprivation.

Happy Fish Sign #4: Your Fish Looks Normal

No, your fish isn’t like a mood ring that changes color to reflect its mood, but there are some visual cues that will tell you if your fish is unhappy. Basically, a happy fish will look as it normally does, and if it starts to look different, there is likely a health problem or stressor involved.

There are several ways that a fish will look different if there is a problem:

  • Loss of color: A fish will lose its color if it is under a lot of stress, and there are a lot of things that can stress a fish out from a new tank to an aggressive neighbor. A fish can also lose its color if it is not being fed a healthy diet as the pigment that gives fish their coloring comes from their food.
  • Patches or gray or white: This is a sign of a fungal or bacterial infection and requires swift action. White spots can also be a sign of Ich, which is a parasitic infection.
  • Frayed tail or fins with white on the edge: This is a sign of fin rot, a condition that usually happens because of poor tank conditions.
  • Popping eyes: If one or both of your fish’s eyes are suddenly protruding, then it likely has Popeye. This is caused by a build-up of fluid behind the fish’s eyes that can be caused by injury or infection.
  • Gold or rusty spots: These spots can be hard to see, but if you notice them, your fish may have a parasitic infection known as velvet.
  • Clamped fins: A fish will hold its fins close to its body when it is ill. But it is not a sign of any particular illness. It is important to determine what is ailing the fish if you see one or more clamped fins.

If you notice any of these differences in the appearance of your fish, you definitely have an unhappy, suffering fish on your hands, and all of them need to be addressed swiftly to prevent death. 

Happy Fish Sign #5: Your Fish Are Breeding

Fish won’t breed if they aren’t happy. It is as simple as that. The more comfortable, safe, and healthy their environment is, the more likely they are to breed. Some fish, like guppies and mollies, breed easily without too much nudging from you, but others will require specific tank conditions like a special substrate or water temperature. 

So, if your fish are breeding, it is a sure sign that they are happy, healthy, and stress-free, but if they aren’t breeding, it doesn’t necessarily mean they aren’t happy.

Here are some other reasons besides unhappiness that they might not breed:

  • Tank conditions aren’t prime: Each fish breed will have its own breeding requirements, and if one of those is not may, the fish may not breed. If you want to breed your fish, you will have to do a little extra research. 
  • Fish breed never breed in captivity: Some types of fish will not breed in captivity no matter how hard you try. You could have the nicest, planted aquarium around, and the fish just won’t breed. 
  • There’s no mate: You’ll need a male-female pair to breed your fish, and they need to want to mate with each other. A female may snub an unhealthy male, for example.

If you aren’t finding baby fish in your tank, and you think you should be, don’t forget that other fish might be eating them before you notice them. Make sure you’re providing a safe place for the fry to hide.

Happy Fish Sign #6: Your Fish Are Acting Normal

In order to know if your fish are acting normal, you need to familiarize yourself with how your fish behave. This means spending time admiring your tank and its inhabitants, which doesn’t sound like a bad way to spend the afternoon.

Here’s what you need to know about normal fish behavior:

  • Aggressive or timid? Some fish hide as a matter of course and others might be more aggressive. Changes in how your fish normally behaves, either becoming more aggressive or less so, is a sign that something is amiss.
  • Alertness and activity level: Besides the aggressiveness or shyness of a fish, you should consider the alertness of the fish. If a fish that is usually zipping around the tank nosing into everyone’s business is suddenly lethargic, it probably isn’t feeling too well.

Changes in behavior can be caused by health issues, tank issues, or stress, all of which impact the happiness of your fish friend.

What if Your Fish is Unhappy or even Stressed

Fish get stressed easily, and it makes a lot of sense if you think about it. In the wild, fish are food for larger fish, predators, and humans. Their only defense mechanisms are the ability to hide, their speed, and their ability to sense danger. This means they notice changes in their environment, and it stresses them out because they’re worried they’re going to get eaten.

Besides making a fish miserable, stress can lead to fish death, so it is important to take it seriously and take care of whatever is causing the stress.

Why Your Fish is Stressed

Because fish get stressed so easily, it can be hard to figure out why they are stressed. There are just too many potential causes!

Here is a list of some of the reasons your fish might be stressed:

  • Overcrowding in the tank
  • Other fish are aggressive
  • Poor tank conditions
  • Loud noises around the tank
  • Lack of hiding places
  • Not enough food or not the right food
  • Illness or injury
  • Changes to their environment
  • Loneliness in Schooling Fish

Some of the things on this list are pretty broad, but don’t worry; we’ll go over many of these later when we talk about how to improve happiness in your fish. 

Signs Your Fish is Stressed

If your fish is stressed, it is clearly not happy. But a fish can’t communicate with you with sounds or expressive eyes the way another pet might. How do you know if your fish is stressed? Here is what you should look for:

  • Hiding
  • Frantic movements (unless they’re normally frantic)
  • Rapid breathing
  • Not eating enough
  • Lethargic
  • Loss of color
  • Changes in behavior

The are many signs of stress in fish, and many of them overlap with common health issues. If your fish is exhibiting signs of stress, you should also be on the lookout for signs of illness.

Solving Your Fish’s Stress Problems

If your fish is stressed, the problem is usually easy to solve. The most common issue is usually the water quality, but it certainly isn’t the only thing to look out for.

Here are our step-by-step tips for troubleshooting what is causing your fish to be stressed:

  1. Check the tank conditions, including the water, temperature, lighting, cleanliness, oxygen, filter, and number of fish per gallon.
  2. Make sure there isn’t another fish bullying your stressed fish.
  3. Does your stressed fish have a place to retreat and hide if it needs to?
  4. Make sure you’re feeding the fish the right diet.
  5. How loud is the environment around your tank? Loud noises can startle fish.
  6. If your fish prefers to school, make sure it has plenty of friends of the same breed.
  7. Check your fish for signs of illness.

If none of these seem to be the cause, you may need to talk to a fish expert or vet to figure out what is ailing your fish. Stress should never be ignored.

How to Make Your Fish Happy

As we said, making your fish happy is as easy as making sure they’re living in a healthy environment that is stress-free, but what all goes into that? In this section, we will discuss the specifics of being a good fish carer and how to go the extra mile to ensure your fish are happy.

Make Sure the Tank Conditions are Good

The tank conditions will have the biggest impact on the health of your fish and their happiness. Below we will discuss some generalizations about how to maintain good tank conditions, but every breed is different, so you will need to do some research on your specific type of fish.

Tank Size and Overcrowing

It is completely understandable that you would want a tank full of vibrant fish and interesting décor, but this might not be so good for your fish. In the wild, fish have all the room they could possibly need to swim around and explore, so you should do your best to make sure your fish have at least the minimum room they need.

  • Large fish must be able to turn around in their tank and have plenty of lateral swimming space so that they get enough exercise to keep them happy.
  • With small fish, you can generally have 1 inch of fish per 1 gallon in your tank. For fish that are short but squat, you should consider 1 inch of fish per 2 gallons to be sure they have enough space.
  • Décor takes up space too, and you will need to take that into consideration.
  • Try to include top dwellers and bottom dwellers in your tank to make sure there isn’t a crowd in any single zone.

It is very easy to overcrowd a tank, so it is always better to err on the side of fewer fish than too many.

Besides the happiness of your fish, you should also note that the more crowded your tank, the more frequently you will have to check the tank conditions and change out the water.

Tank Water Quality

The quality of the water in the fish tank is, of course, critical to the health and happiness of the fish.

  • Ammonia and Nitrite: You probably don’t think about it all that much, but fish poop in their water. This leads to a build-up of harmful chemicals like ammonia and nitrite. You can test your tank water regularly using a test kit, which is much better than waiting for signs of stress in your fish.
  • pH: The pH level of the water is also important, but how important and what pH is best depends on the type of fish you have. Most fish require a neutral or near-neutral pH.
  • Oxygen: Fish might not have lungs, but they do need oxygen to breathe. It is important that they have the right amount of oxygen in their tank. To ensure your fish have enough oxygen, you should regularly change the water and equip the tank with a bubbler and a filter. 
  • Water Filter: Use a water filter in your fish tank to help keep it clean and be sure to follow the suggested maintenance practices for it.
  • Avoid Tap Water: Most of the time, dechlorinated tap water is fine for use in a fish tank, but you should test your water to be sure the pH isn’t off. If your water is overly hard or soft, it may not be suitable.
  • Lighting: Most tanks come equipped with some sort of light, and this is a good thing. You should try to mimic natural light by turning the tank light off during the night. Also, make sure your tank is not in a lot of full sun as this can cause excess algae to be low.


To help keep your tank fresh, you should clean it regularly. How often will depend on the size of the tank and the number of fish you have in it. Many recommend taking out about 10% of the water in the tank and refilling it once a week in between deep cleanings.

Fish Tank Temperature

In general, a fish tank should be somewhere between 75 degrees Fahrenheit and 80 degrees Fahrenheit, according to Tropical Fish Magazine, but this is another thing that will depend on the type of fish you have. Some can tolerate much colder or warmer temperatures.

Unless you can keep your home 80 degrees year-round without any interruptions, you’re going to need a tank heater and a thermometer. Because low temperatures will kill fish, it is recommended that you equip your tank with two heaters so that if one goes out, the other can pick up the slack. Bear in mind using AC in the room with a fish tank.

Fish Tank Décor

Tank décor is a little talked-about way to keep your fish happy. Most fish, even fish who aren’t particularly timid, appreciate a place to hide once in a while, and adventurous fish like to explore. Here’s what you need to know about tank décor:

  • Tank décor can influence the water conditions of your tank. Certain substrates, plants, and woods can alter the pH of the tank. Depending on the pH of your water, this could be good or extremely bad.
  • Too much tank décor will overcrowd your fish.
  • Changing tank décor will cause a brief period of stress for your fish. Imagine if someone plunked down a new house where your old one was. You’d be stressed too.
  • You might need to clean tank décor unless you have very proficient algae eaters.
  • Some types of fish prefer certain types of décor over others. Be sure to do your research, and what do not put in the fish tank.
  • Some fish will use décor like caves for spawning purposes.

Find Good Tank Mates

Now that you know what your tank conditions should be let’s talk about the living things you are putting in it. Finding good tank mates for your fish is crucial to the happiness of your fish. No fish wants to live under constant harassment by a bully or in fear of being eaten by a much larger fish that it cannot escape. It’s the stuff of horror movies!

  • Provide lots of places to hide. Even with fish that get along well, it is best to give them plenty of places to relax if they’re feeling unsafe.
  • Research good pairings. There is a wealth of information on the web about which fish play nice with other fish. For the happiest fish, select only those that get along exceedingly well, or stick to a single type of schooling fish.
  • Avoid putting large and small fish in the same tank. Large fish will eat small fish. It is just a fact of life. If you are putting large and small fish in the same tank, it is best to provide a lot of places for the small fish to hide and keep your big ones well-fed. Your smaller fish will probably still feel stressed about the deadly potential of their neighbor.
  • Be careful with aggressive, territorial fish. Some types of fish are more territorial or aggressive than others. You need to provide them with extra space and areas that they can claim as their own. This will keep them happy. However, for the sake of others in the tank, you have to be careful who you pair with them.

Choosing Fish for Your Tank

Ensure Proper Nutrition

Providing your fish with the right nutrition is essential. Most small aquarium fish only require the standard fish flakes to provide them with a healthy balanced diet, but some fish require specialty pellets or additional protein. Once again, you’ll need to research the specific fish you have to know exactly what to feed them.

But if you want a really happy fish, you’ll want to provide occasional treats. Depending on the type of fish you have treats can include:

  • Zucchini
  • Cucumber
  • Brine Shrimp
  • Mealworms
  • Live insects

Treats should be given in moderation to prevent overfeeding, but your fish will be happy to have a break from the monotony of the fish flakes. Read more in the article – run out of fish food.

Do Your Research

There is no replacement for doing proper research on the type of fish you have or are planning to add to your tank. Fish breeds are truly unique, and what works for one can be disastrous for another, even among the easier breeds.

So, take the information we have given you in this article as a place to start and begin doing more specific research on your fish breed. There is plenty of information online, and people waiting in forums to discuss the best ways to care for fish.

Is Your Fish Happy?

Some may argue that fish don’t have the emotional capacity to feel happy, but whatever the naysayers argue, it is plain as day to see when a fish is miserable.

If you are worried that your fish are unhappy, then take heart. It is not difficult to ensure the happiness of your fishy friends. Just take good care of them and make sure they are free of illness and stressors, and you’re fish is sure to as happy as a clam.

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