As carnivores, bettas have a relatively short digestive tract, and with a diet that consists mostly of protein and relatively little fiber, bettas are prone to constipation. This is a problem that needs to be addressed/prevented as it can compound and become very serious if ignored.


The leading causes of constipation in the home aquarium are suspected to be:

  • Overfeeding; and
  • Feeding the wrong foods.

Feeding foods such as dry pellets and freeze dried foods can very quickly constipate bettas as, when they are rehydrated inside the betta, they expand and clog the digestive tract. As mentioned in the FEEDING section, these foods should be soaked prior to feeding, and live/frozen foods can be fed whenever possible


Note that otherwise the betta should appear and  behave relatively normally. A distended stomach accompanied by loss of color, lack of appetite, lethargy, and especially protruding scales can be (and in the case of protruding scales, are) symptoms of more serious underlying illness and need to be addressed as such.


The swollen/bloated stomach of a constipated fish is not to be confused with the bloating of a fish experiencing DROPSY, which is entirely different.


  1. If a betta does become constipated, he/she should be first fasted for 1-3 days to see if the digestive system can clear itself out.  This also prevents worsening of a blockage.
  2. If a brief fast is not successful, the fish can be fed a portion of daphnia which acts as a mild laxative
    1. Feeding a small portion of a blanched pea (instructions for preparation are below) is also used to remedy constipation, but daphnia may be preferable, as vegetable matter is not naturally in a betta's diet.
  3. Pure, unscented epsom salt can be added to the tank water to help ease severe constipation.
    1. Make certain that the only ingredient is epsom salt and that there are no added scents, or other ingredients.
    2. The maximum dosage that should be used to treat constipation is 1 tablespoon (1 tbsp) per 5 gallons of tank water volume.
      1. A good starting dose is 1 teaspoon (1 tsp) per 5 gallons and to increase if no response is seen, or if the constipation is severe
    3. Epsom salt is compatible with all medications
    4. Note that epsom salt will not be absorbed by any chemical media, such as activated carbon, and will need to be removed via water changes once treatment is done

A suggested procedure for feeding a blanched pea is as follows:

  • Choose frozen, unseasoned peas over canned or prepared varieties, as those may have preservatives and/or additives that are dangerous to or at least not good for bettas.
  • To blanch, boil a few frozen peas for about 4 minutes, then run cold water over them to cool. Some may fall apart during this process, but some will be left whole to use in the next step.
  • Remove the skin from the pea and cut it with a paring knife into pieces the size of a regular portion of food for the betta and feed to your fish.