Bettas are prone to a number of different conditions involving and related to bloating and swelling. It’s important to know what is normal for your betta and what is abnormal. Spend some time observing your betta on his or her good days so that you will know immediately when something is bigger than it’s supposed to be and react accordingly.

Bloating and Swelling

1. Bloating and constipation
2. Swim bladder disorder
3. Dropsy
4. Popeye

1. Bloating and Constipation

This is one of the most common problems bettas encounter--usually due to lack of experience on the fish keeper’s part in terms of what they feed their betta, how much they feed their betta, and how they prepare the food. Bettas were not designed by nature to eat dry, bready, air-filled foods--when you feed dry food to an aquatic animal, they go through something similar to us when we eat uncooked rice or noodles. The food expands in the gut as it absorbs moisture--causing bloating, discomfort, and constipation. It’s important that whenever you feed your betta dry food, be it flakes, pellets, or freeze dried, that the food be fully hydrated for a few minutes in a little tank water before use. Freeze-dried foods should be used sparingly, if at all, since they are responsible for much of the worst constipation in bettas. If the food is prepared correctly and the betta is not overfed, you will likely never deal with constipation and bloating. If you are feeding correctly and you come across bloating and constipation, you should be sure that your betta is being kept at the appropriate temperature--as all of the metabolic processes, including digestion, in cold blooded animals are dependent upon warm, stable temperatures.


Physical: The abdomen is visibly distended, when a light is shown through the fish, the distended area is opaque. The fish will not pass feces.

Behavioral: Usually no change is evident, the fish may be less active or hide often.


Minor bloating and constipation: Fast the fish until the swelling goes down, or you see the fish pass feces. Slowly adjusting the temperature up a couple of degrees and feeding the fish a small amount of fibrous food can help expedite the process. Frozen (wet) daphnia and brine shrimp are good high fiber choices. If you happen to have frozen (not canned) peas instead, you can dip a bit of paper towel in tank water, wrap a single frozen pea in it and microwave for a few seconds. Remove the shell of the now cooked pea and you will see that the inside is made of two halves--crush one of the halves and form it into a small ball (smaller than a pellet) and feed it to the fish. You should see a reduction in bloating or feces within the week. Try to make note of the appearance of the feces, if it is white, stringy, or otherwise abnormal, see entry for Internal Parasites.

Severe bloating and constipation: When the minor treatment is not enough, you should consider an Epsom salt bath or leave-in treatment.

*When using Epsom salt with other medications, make sure that the medication does not warn against the use of sulfates or sulfa drugs. Epsom salt is magnesium sulfate and could interact badly with some medications.*

Epsom Salt Bath: In a separate container, prepare water of the same temperature or use water from the betta’s tank and dissolve 1 tablespoon of Epsom salt per gallon. Slowly adjust the betta to the water over about 5 minutes--acclimation time is much shorter because the fish shouldn’t be exposed to this amount of Epsom salt for too long--then allow the betta to sit in the bath for 15 minutes. Carefully monitor the betta, and remove him or her if they show signs of distress. Consider changing the water in the betta’s tank during the bath so that the fish will have clean water to recover in. This treatment can be repeated once in the same day, but if repeated, the duration of the bath should be shortened to 5-10 minutes.

Epsom Salt Leave-in Treatment: In a separate container, prepare water of the same temperature, and mix in one tablespoon per five gallons of dissolved Epsom salt. Acclimate the fish to the salted water for at least a half hour. Alternatively, if you used water from the betta’s tank, you can transfer the betta into the water directly and dissolve the salt in another container--slowly adding the dissolved salts to the water over the course of at least a half hour. The duration of this treatment is three to five days--during this time, do water changes as necessary, replacing the dissolved salts as necessary.

2. Swim Bladder Disorder

Swim bladder disorder (SBD) is more of a symptom or a condition than an actual disease. It can occur for different reasons, such as injury, or birth defects, but the most common cause of this disorder is bloating and/or constipation. Bloating in the abdomen puts pressure on the swim bladder, which is the organ responsible for giving the fish control over its depth in the water. Pressure or injury can cause the swim bladder to malfunction, causing the fish to sink or float uncontrollably. In most cases, the fish will return to normal within a few days, but if the fish was born with the problem or the swim bladder is irreparably injured, the fish can still live a normal, happy life with this handicap as long as he or she is properly accommodated.


Physical: The fish strains to the top and sinks like a rock or floats uncontrollably with a small amount of the fish’s topline protruding from the water. The fish may roll over on its side, and often moves its body into the shape of an ‘S’ as it attempts to balance itself and remain upright in the water.
Behavioral: The fish may be less active, stressed, and often hide because their condition makes them feel vulnerable to predation.


Make the fish as comfortable as you can. If the fish is a floater, make sure that there are plenty of floating plants to hide in and hide under--I usually float an Indian almond leaf, a piece of Styrofoam, or the cut-out center of a paper plate on the surface of the water so that they have something to hide under. If the fish is a sinker, lower the water level to make it easier for the fish to reach the surface. Make sure there are plants or other objects that the fish can rest on close to the surface.

If the fish is bloated and showing signs of SBD, see entry for Bloating and Constipation.

3. Popeye

Like SBD, Popeye is a symptom of a disease, rather than a disease in itself. It is characterized by one or both eyes swelling up to more the twice their normal size--if left untreated, the fish can lose its eyesight and its eyes as a result of this condition. In order to treat popeye, one must figure out the underlying cause. It can be caused by eye injury (particularly if only one eye remains affected), poor water quality, nitrogen gas bubble disease, poisoning, and internal bacterial infection (particularly if both eyes are affected).


Physical: One or both eyes are swollen and protrude abnormally, may have the appearance of a light film over the eye as well.
Behavioral: May be less active, hiding, lethargic.
The fish may exhibit a wide range of other symptoms depending on the underlying cause. The fish may also be vulnerable to secondary infections such as saprolegnia and external parasites.


A 100% water change will help remove the danger of poor water quality and poisoning. Test the old water before disposal to eliminate water quality as a possible cause. If the swelling is severe, consider an Epsom salt bath--for instructions, see treatment entry for Bloating and Constipation. Examine the eye for signs of injury, such as a scrape or cut around or in the eye. If no injury is evident, and the fish is hiding, lethargic, and otherwise behaving ill, see entry for Internal Bacterial Infections and proceed from there.

4. Dropsy

Dropsy can also be seen as a symptom of a disease, rather than a disease itself. Dropsy occurs as a result of a failure in kidney function. Due to this failure, the fish retains fluid that builds up under the skin, causing the fish to appear bloated and for the scales to stick out from the body like a pinecone. Normally, when looking down at the fish from above, the sides are smooth with no distinction of where one scale ends and another begins. If, while your fish is ill, you notice that the scales are sticking out even slightly, you should begin treatment immediately, as dropsy is only treatable within the early stages. If the fish is severely pineconed, chances are, the fish is beyond saving. Damage to the kidneys can be caused by overmedication, bacterial infection, and poisoning.


Physical: The fish appears bloated, and from a bird’s eye view, the scales appear to stick out from the body. The fish may show SBD-like symptoms, and often is in vertical nose-up or nose-down position.
Behavioral: The fish is often lethargic, shows little to no interest in food, and is listless.

Pineconing, bloatings.
Pineconing, bloatings.


Immediately begin an Epsom Salt Bath treatment. For instructions, see treatment entry for Constipation and Bloating. If the fish is very ill and stressed out, the leave-in treatment may be a better alternative. Make the fish as comfortable as possible during treatment. Do not use aquarium salt/kosher salt.

See entry for Internal Bacterial Infections.