A betta fish not interested in eating is a common issue for many betta owners. Thankfully, there are a few things you can investigate before you need to ask for help from a veterinarian. Most of these relate to inappropriate husbandry, or how well you take care of your betta. Making a few small changes as soon as possible will considerably improve the chances that your betta will return to normal eating.
Causes of Betta Fish Not Eating
There are a few causes to why your betta fish may not be eating. It can also be a combination of the following factors:
Fish that are in poor water quality get stressed. Because fish cannot escape this environment, though some may jump out of their tank or bowl trying to do so, the constant exposure to bad water results in a chronic stress state. With a fish's immune system on stress overload, they don't feel well, and as a result, have lower immune function, reproductive effort and growth, and reduced appetite.
Thankfully, poor water quality is one of the easiest things to fix. Get your betta out of that antiquated bowl and into a five to 10 gallon heated, filtered aquarium. Test your water quality regularly with a liquid-based test kit and do your regular maintenance so your water quality parameters stay within normal ranges.
Poor Quality Food
No betta will ever actually finish a container of betta food in a timely manner. If the containers were the appropriate size, you'd never find them on the pet store shelves! After about six months, fish foods will lose most of the water-soluble vitamin content, including vitamin C. Not to mention that all food gets stale after being opened repeatedly every day. Bettas rely on their sense of smell to find their food and if it's getting old, it does not smell very good.
All bettas should be fed two to three times per day. Use a fresh pelleted diet that is replaced at least every six months. Due to varying pellet size, feed as many pellets per meal that could theoretically fit within one of your fish's eyeballs.
Feeding old food for too long can have serious consequences for your fish's health. Old food loses its nutritional value, especially vitamins. Without immune boosting vitamins C and E, your fish is significantly more prone to secondary infections from the surrounding environment.
Some bettas have eyes bigger than their stomachs and will happily consume all morsels in their tank. However, if their metabolism cannot keep up, food starts to get backed up and can cause serious GI distress. Overfed bettas can present with severely distended bellies and will need help ASAP. Bettas should be fed twice daily, but only a small amount of food each time: about as many pellets as would equal the size of their eyeball. Any uneaten food that remains on the bottom of the aquarium should be removed with a net or gravel vacuum.
Bettas are tropical fish and therefore require a heater in their tank. Pet fish are ectotherms, meaning their metabolism and immune function is dependent on their surrounding environmental temperature. Various species of fish have a "sweet spot" for temperature ranges in order to be in optimal health. Bettas require heat around 78 to 82 degrees Fahrenheit (25 to 28 Celsius). Be sure to use a commercial aquarium heater designed for the size of your aquarium. Larger heaters may be too big for a Betta Aquarium's small volume of water, so make sure you check your heater's function by having a submerged thermometer in your betta's tank.
If you do not have a heater and your water is too cold, your betta cannot properly digest their meal. This can lead to an impaction where the gastrointestinal (GI) tract fills with food and cannot exit the fish. Affected fish will present with severely distended bellies and need to be seen by an aquatic veterinarian.
Betta fish are notorious for viciously defending their territory. Male bettas should never be kept together or even within sight of each other. Some female bettas can also be very aggressive, depending on their individual temperament. Fish that are too concerned about their tankmates can easily become stressed and stop eating.
Illness and Disease
Even with the best care and housing, your betta can still become ill. If you have checked off all of the above points and can still not figure out what is wrong, it's time to call a professional. Especially if you see other serious signs of illness, such as lethargy, change in color, rips or tears in the fins or pine-coning of the scales. The sooner you get your betta help, the better the prognosis will be.
If you notice your betta is not eating, the first thing to do is test your water chemistry. If any of your parameters are off, especially temperature, take steps to correct it as soon as possible. Remember, any changes to pH or temperature should take place very slowly so you do not shock your fish.
If your water quality is all within the normal range, assess your betta's diet. When did you buy it? Does it look and smell like it did when you first bought it? Any suspicious or old diets need to be replaced.
Once you have assessed any environmental or dietary issues, you should call your aquatic veterinarian for additional guidance and diagnostics.
How to Prevent Decreased Appetite
The best method to ensure a happy and healthy betta is to house them in a heated, filtered aquarium, keep their water chemistry within range and feed them appropriately. If you have any concerns about their health or husbandry, contact your local aquatic veterinarian.
Roberts HE. Fundamentals of Ornamental Fish Health. Wiley; 2009.