Stressed Betta Fish – Causes, Symptoms, & Effective Treatments

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    Sooner or later, all betta fish owners will come across a day where you have to treat a stressed betta fish. Perhaps its colors have dulled or it’s swimming along the bottom. What happened and how can we help our stressed fish?

    There are many reasons why you may have a stressed betta fish. Poor water quality, an aggressive tank mate, cold temperatures, and disease will all stress a pet betta.

    In this guide to betta fish care, we’ll be exploring how to diagnose stress in betta fish. As well as how to treat the most common causes of stress in an effective manner!

    How To Tell If You Have A Stressed Betta Fish – Common Signs & Symptoms

    Stressed betta fish symptoms

    Identifying a stress sign can be difficult if you are still new to aquarium fish care. This bulleted-list provides you with a ready guide to identifying the most common signs of stress in betta fish:

    Common Signs and Stress Behaviors in Bettas:

    • Clamped fins
    • Pale colors
    • Lethargy (won’t swim freely)
    • Lack of appetite
    • Betta stress stripes
    • Disease symptoms

    Lethargy In Betta Fish

    Lethargy in a normally active pet is a major sign that you have a stressed betta fish. A healthy betta fish spends most of its time scouting around the tank for morsels of food. They also watch their tank mates and you when you move around.

    A lethargic betta fish shows signs of stress by losing interest in swimming around. It will hang in the water in a single place. Sitting along the bottom of the tank or at the surface is a sign of stress in all aquarium fish, including bettas.

    Lack Of Appetite

    Betta fish normally eat with gusto. In fact, they eat so much that their stomach swells up after a good meal. Any lack of appetite in a betta fish is a sign for you to look closer for possible problems.

    A lack of appetite can also mean nothing. If you recently fed your betta fish it might not be interested in another meal just yet. So long as it is otherwise colorful and active I would not worry just yet.

    But skipping more than a single meal suggests you have a stressed betta fish. Especially when combined with the other signs of stress outlined here.

    Pale Colors And Betta Stress Stripes

    Another sign of betta stress is a change in the colors of your fish. Many fish species, including bettas, will grow pale when they are not feeling well.

    Even a bright red or blue betta can fade to grey as stress arises. As these vibrant colors diminish you will also see stress stripes along their flanks.

    Betta stress stripes are patches of pigment that don’t fade as stress develops. Betta stress stripes arise for a number of reasons. Illness, fear of an aggressive tank mate, and cold temperatures can all cause stress stripes to appear.

    Disease Symptoms

    This category of stress in betta fish is more diverse because diseases can show up in all kinds of ways. Ich, fin rot, dropsy, and other diseases often arise when an initial stressor weakens the immune system of a betta fish.

    When this happens you then have two problems to deal with at once. So it’s always best to diagnose and treat a stressed betta fish as soon as the first symptoms arise.

    Here are some common disease symptoms in betta fish to consider:

    • White cysts or patches of cotton-like growth
    • Cloudy eyes
    • Excess skin mucus
    • Frayed or clamped fins
    • Inflamed blood vessels in fins
    • Protruding scales
    • Body bloat

    Causes (And Treatments) Of Betta Fish Stress

    How to treat stressed betta fish

    Now that we’ve determined how to identify a stressed betta, let’s take a look at the main causes. From there, we will outline solutions to reduce stress in your pets!


    Causes of Stress in Betta Fish Stress Treatments
    Poor water quality Use a water test kit to determine which parameter is causing stress. Perform water changes as needed to bring levels back to normal.
    Aggressive tank mates Identify the aggressive tank mate; move either the betta or the bullying fish. Treat any wounds using stress coat to prevent infection.
    Cold water temperature Use a heater to raise the water temperature past room conditions. Choose a heater rated for your tank size.
    Betta fish diseases Diagnose the disease and apply the proper medication and treatments. Isolate your betta fish in a quarantine tank, if possible.
    Shock from sudden changes Turn off the aquarium lights and don’t feed for one day. Give your betta fish time to adjust to any sudden changes and monitor for any more signs of stress.

    Poor Water Quality

    Betta fish are popular because they are very hardy aquatic pets. But poor water quality is one of the most common reasons why stress in bettas is so common.

    Aquarists who are told how tough bettas are can become lax with aquarium maintenance. They skip water changes, instead just topping off evaporated water in the tank to save time.

    Filter maintenance gets put off, day after day. And before too long, you start seeing betta stress stripes and other problem signs.

    Poor tank parameters include chemistry issues like elevated ammonia and nitrate levels. Ammonia is released by fish as a waste product. It also forms when leftover food and fish poop decays.

    In a healthy aquarium, this ammonia is processed by the beneficial bacteria in the water. It gets converted first to nitrite and then nitrate. Nitrate then accumulates in the tank until you remove it with water changes.

    All aquarists should have test kits on hand. These help you monitor whether ammonia and nitrate levels are in the safe zone for their betta fish. If your test kits show that your water parameters are no longer safe, a large water change is the first thing you need to do.

    Aggressive Fish Tank Mates

    Betta fish are famous for being aggressive fish. But they can sometimes be bullied even harder by other aggressive fish. Bettas are temperamental but their long fins and lack of teeth make them easy targets.

    Aggressive tank mates with speed and teeth can make life difficult for a betta fish. Even fish that aren’t really ill-tempered may find the flowing fins of a betta fish irresistible.

    Fast-moving fin nippers like tetras and barbs will pick at bettas and other easy targets. These bites not only cause betta stress; they also open up wounds for bacterial and fungal infections to arise.

    A betta that is feeling bullied will spend time near the top of the aquarium. It will have pale colors, showing its stress stripes.

    The betta will likely hold its fins clamped against its body. This behavior protects them from being bitten. You may also see tattered edges to the fins, evidence of attacks from an aggressive tank mate.

    To give your betta fish a stress-free life it needs to be the dominant fish in the aquarium. Any other fish species that are too much to handle should be moved to a separate tank. Or you can move your stressed betta since betta fish do fine as solitary fish.

    Fin Nipping and Aggressive Tank Mates Include:

    • Cichlids
    • Gouramis
    • Larger Killifish
    • Tetras
    • Barbs and Danios
    • Other Betta fish

    Cold Water Temperature

    Low water temperatures are a major reason why stressed bettas are so common. While they tolerate brief periods of cold bettas are truly tropical fish. They are found in Thailand, where temperatures rarely go below 70℉.

    Night-time temperatures below this are fine. But during the day the water temperature should remain at 75-84℉. Cold water causes tropical fish to become lethargic, eat less, grow slower, and develop diseases more frequently.

    Like most fish, betta fish are ectotherms, meaning their metabolism is regulated by the environment. They depend on tropical fish conditions to maintain good health. A small heater is an important addition to any betta fish aquarium.

    Once you raise the water temperature your betta fish should lose any stress stripes and lethargy. If cold was the problem it will also be ready to eat a hearty meal soon.

    Warmth is also a great way for fish keepers to treat betta fish diseases. Increasing the temperature to 84-86℉ boosts the activity of the fish’s immune system. The life cycle of many fish parasites also happens faster.

    Coupled with the use of the right medicine, a simple heater can help most fish diseases come to a faster end.

    If your betta fish aquarium is smaller than five gallons, make sure you use a heater rated for tiny tanks. A heater that is too large can warm the water to dangerous levels. This submersible heater is rated for tanks 1 to 10 gallons in volume; ideal for a solitary fish!

    Betta Fish Disease Treatment

    Even beginner fish keepers know that diseases come in many forms. Identifying and treating individual diseases are a subject that takes up several additional articles.

    Fortunately, this website is full of guides on dealing with common betta fish diseases like velvet and swim bladder disease.

    This video also does a great job of explaining how to identify diseases:

    YouTube player

    If you can, I also recommend isolating a sick betta from other fish. Diseases can spread, especially contagious ones like ich. And even if you cure your betta fish it can pick up a disease once again from sick tank mates.

    A quarantine aquarium is a small tank with a heater and a filter. You can treat a sick fish without it having to compete for enough food. A fish that is too ill to eat quickly may become even sicker if it can’t eat properly.

    Any medications you use won’t cause stress to sensitive tank mates like invertebrates, either. Copper-based medications, for example, are great for treating ich and other parasites. But they can easily kill aquatic shrimp and snails, which are also invertebrates.

    Shock From Sudden Changes

    A stressed fish may also be reacting to sudden changes in its environment. When you bring a betta fish home from a pet store it may not eat for an entire day.

    The shock of a major change in water conditions and tank decorations may be too much at first. Betta fish feel secure in an environment with few major changes.

    Housing bettas alone is very common. And a change from living alone to joining an aquarium full of other tank mates can cause minor stress. A betta fish introduced to a community tank may immediately retreat to hiding spaces.

    If shock from a new environment is the cause, there is little you need to do. Simply wait until your betta fish feels safe enough to relax. With time it will grow hungry and start exploring its new home.

    How To Calm A Stressed Betta Fish

    Once you’ve identified the reason why you have stressed bettas treating the problem is just the first step. Consider taking one of these next steps to further reduce stress in your pet fish!

    Turn The Aquarium Lights Off

    When a fish is stressed it is not going to spend much time looking for food or engaging with its tank mates. It will be trying to hide and rest. Turning off the aquarium lights helps fish do just this.

    This is similar to taking a nap when you aren’t feeling well. Lowering the amount of time lights are on reduces how much energy your betta fish spends.

    If you have live plants then you won’t want to keep the lights reduced for longer than a few days. But a short period of reduced light won’t cause your plants lasting harm.

    Make sure you do turn the lights on when you are ready to try feeding your stressed betta, however. Give your betta fish a few minutes to wake up fully and explore. That way, any food you add won’t be wasted, which would cause ammonia levels in your tank to rise.

    Perform Water Changes

    Water changes are one of the most reliable tasks fish keepers can engage in if a fish is stressed. Poor water parameters include a whole host of problems; high ammonia and nitrate levels are just the most common. But there may be a parameter out of balance that you don’t have a test kit for.

    Doing a water change flushes out pollutants, pathogenic bacteria, fungal spores, stress hormone chemicals, and feces. All of which cause a betta stress by impacting water quality.

    25% to 50% water changes are safest. But any more can actually increase stress since the water parameters can shift so wildly. Only change more than 50% at a time if you know that your betta fish is stressed due to high ammonia, nitrite, or nitrate levels.

    First, perform the water change. Refill the aquarium and then use a test kit to determine how high the pollutant concentration is.

    If you are still in the danger zone, then perform a second water change and retest.

    An efficient filtration system should never allow nitrogenous waste product concentrations to become so dangerously high. But if you have a brand new aquarium setup, sometimes you will see ammonia levels rise fast at first.

    This is known as new tank syndrome. This condition arises when you are keeping fish in an aquarium that does not have enough beneficial bacteria to break down ammonia.

    New tank syndrome is dangerous because once fish start to die, ammonia levels remain high. This pollutant then kills any other fish you add to the tank until your bacteria are fully established.

    Add Aquatic Plants

    Aquatic plants are very helpful for reducing stress in bettas. Plants use ammonia, nitrite, and nitrate as fertilizer. They also absorb the CO2 that bettas breathe out, converting it into oxygen for fish to breathe back in.

    Wild betta fish are well adapted for living among plants. They will rest on plant leaves and thread their way through aquatic thickets, looking for mosquito larvae and other insect prey. Bettas also prefer building their bubble nests in hiding places among floating plants.

    Plants are inexpensive, beneficial, and very decorative. Just make sure that your tank has enough light of the right spectrum for photosynthesis. Plants can’t grow under just any lighting.

    They need photosynthetically active radiation (PAR) to thrive. Standard aquarium hoods don’t output much PAR, unfortunately. But floating plants will often do well since they sit so close to the bulbs. What little PAR fluorescent hoods create is still enough for these plants.

    A few good floating plants that make a betta happy include duckweed, hornwort, and red root floaters! Floating plants also reduce light levels beneath them.

    While this can make submerged plants harder to grow, betta fish don’t mind low light levels. The dim conditions lower stress by helping fish feel less exposed to predators.

    Add Stress Reducing Agents to Your Water

    As a general tonic, API Stress Coat is a product that every fish keeper should have on hand. It includes agents that detoxify chlorine and chloramine. So you can add it every time you perform a water change to keep stress levels low in betta fish!

    Stress Coat uses aloe vera as a soothing stimulant. It boosts the slime coat of fish, which allows wounds to heal properly. The slime coat is a natural barrier to infectious germs.

    Make sure you use this product after performing a large water change. In doing so, you will see an immediate boost in color and activity in a stressed betta fish!

    Aquarium salt is another slime coat stimulant you can use. It also helps reduce stress even further by facilitating ion exchange across gill membranes.

    Don’t forget; salt also remains in the water until removed via water changes. So never add additional salt when topping off evaporated water. Or you may end up raising salt levels to dangerous levels.


    There are many reasons why you have a stressed betta fish. But this guide covers all of the most common causes and how to treat them. From cold temperatures to bullying tank mates, there is always something you can do to reduce stress levels.

    Just remember that you may have to perform several of these solutions at once. Only then will your betta fish lose its stress stripes and return to its usual perky self!

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