Is My Betta Fish Too Fat?

How to determine if your betta fish is too fat

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Body condition in all pets is a very important influence on overall health and wellbeing. Fish are no exception to the rule. Obesity in pet fish can be a critical issue, and even though their joints will be just fine, internal fat clogging various organs can be a serious health concern. But how can you tell if your betta is too fat or too skinny?

Why Do Bettas Get Fat?

Like all pets, bettas rely on humans for their daily diet. The internet is awash in conflicting information on how much, how often and what food to feed your betta. We've cut through the misinformation to give you the straight story on betta diet from a certified aquatic veterinarian with over 8 years experience in pet fish health and wellness.

Bettas get fat when they take in too many calories and do not burn enough of them swimming around. They can also get fat from ingesting the proper amount of calories, but too many calories are from fat and not enough from protein. Protein is the most important ingredient in a fish's diet and making sure your fish gets all the essential amino acids from the protein is critical to their health.

Too many treats, or food items high in protein or fat without a balanced nutrient profile, can also contribute to betta obesity. Although they may eat more foods in the wild, bettas in captivity have a significantly different lifestyle and are more sedentary than fish in the wild.

Bettas can also get fat if their metabolism is too slow from cold water. Betta's are tropical fish and require water temperatures around 78-82F (25-28C). If your water is too cold, your fish cannot digest their food properly. This can also cause lethargy since your fish will not have enough energy to swim around.

How to Quantify Body Condition in Bettas

How can I tell if my betta is too fat? Well, it comes down to body condition scoring, a method similar to determining if your cat or dog is too fat or too skinny, but with some differences. In fish, overall body condition should be determined from a dorsoventral view, or looking down at the top of your fish.

Observe where your betta's body meets the head. The head and shoulders should have the same girth. Your fish's internal organs are located in the coelomic cavity, just behind the head and they end about half to 2/3 of the way down the body toward the tail. A betta with good body condition should be torpedo shaped with a gradual tapering from head to tail, and If your betta's belly is poking out beyond the girth of his head, your betta is overweight. If your betta's body gets significantly thinner just behind his head, your betta is too skinny.

Betta fish with good body condition
From a top-down view, this betta fish has optimum body condition where the shoulders and head are of the same width, then the body slowly tapers off.

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Treatment

Once you have determined your betta's body condition, or had a diagnosis from an aquatic veterinarian, start with some simple diet changes. You should be feeding your betta twice a day, since they are tropical fish in a heated aquarium. Feed a betta food that lists on the label the contents having approximately 35-42% protein and <10% fat. You should feed enough pellets per meal that would theoretically fit within one of your betta's eyeballs per meal. The fish should be able to consume all of the food given in 3-5 minutes per feeding, with no leftover food after that time.

High protein treats, such as bloodworms or brine shrimp, should only be fed 1-2 times per week.

Bettas fed too much and/or kept in inappropriate environments can be prone to impactions. This is a very serious health concern with limited treatment options. If your fish is not passing any feces or starts to develop dropsy, AKA kidney disease, contact your aquatic veterinarian ASAP. Be sure to monitor the water quality to keep your betta in ideal conditions.

How to Prevent Fat Bettas

The best prevention method is to educate yourself on proper betta husbandry and diet prior to purchase. Rather than grabbing whatever is cheapest on the pet store shelf, take some time to review nutritional profiles on fish food packaging and make the best decision for your fish.

Be sure to replace your betta's food regularly. It is almost impossible for one fish to finish an entire container of betta food in an appropriate time. After 6 months, your fish's food has lost most of the water-soluble vitamin content, including vitamin C. Replace your fish's food every 6 months for best health.

Monitor how much food your fish can eat in 3-5 minutes, twice daily and only give it that much food. The amount can be adjusted based on its body condition, described above. Be sure it is not overeating. Over weight fish will have a shorter life span.

What If My Betta is Too Skinny?

If your fish is too skinny, start by increasing their diet. You may want to feed smaller, more frequent meals at first if your fish is struggling to swim. Try to feed sinking pellets so your fish does not have to spend additional calories chasing his food.

Be sure your diet is at the appropriate nutritional levels (35-42% protein and <10% fat) and was opened within the last 6 months for optimal vitamin content.

If you are feeding a proper diet and your fish is not gaining weight, you need to consult with your aquatic veterinarian. There is a increased chance of diseases, such as a mycobacterial infection, in cases of poor nutrition.

Article Sources
The Spruce Pets uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. James, Raja, and Kunchitham Sampath. "Effect of animal and plant protein diets on growth and fecundity in ornamental fish, Betta splendens (Regan)." (2003).