Pets do not come with specific feeding instructions. For fish, which have varying diets and multiple online recommendations, it can be hard for most owners to know how much food is appropriate for their bettas. As long as your betta is living in a filtered, heated aquarium, your fish has a strong start on a long, healthy life. How much to feed your betta will depend on a few key factors and how much time you spend around your aquarium.
Preparing to Feed Your Betta Fish
How much to feed your fish starts with what you should be feeding them. Being tropical fish, betta's metabolic needs require them to have higher calories in their diet. Bettas have to drag along an ornate tail, which requires more calories and lots of rest periods Research has demonstrated that the dietary protein level in betta fish should be around 35%, and can be a mix of plant and animal protein. Although wild betta fish consume an insect-heavy diet, most pet bettas will be fed a commercial diet that will also promote good health.
When it comes to commercial betta diets, pellet size will vary widely. It is hard to give a number of pellets per feeding that will be consistent for all commercial diets. No matter what diet you choose for your fish, do not expect one betta to actually finish all the food in a container before the food become stale. After about six months, the water soluble vitamin content, including Vitamin C, has diminished in quality. You will need to replace your betta's container of food before they actually finish all of it.
How Much to Feed Your Betta Fish
Given the variation in pellet size in commercial diets, the best recommendation for betta fish feeding is to consider your fish's anatomy. For one meal, feed your betta the same amount of pellets that would theoretically be the size of one of its eyeballs. Depending on the diet you select, this could be as few as two or three pellets, or as many as 10 to 12. If you have to feed more than eight pellets, start with half of the amount, allow your fish to finish eating, then feed the second half. The betta should be able to eat all of the food in about five minutes time.
But what about frozen and freeze-dried protein-rich diets? Yes, we know that wild bettas subsist mainly on high protein insect diets, but the lifestyle of a wild fish is significantly different from those in captivity. Wild fish have to live through periods of fasting, when food is scarce, fight other fish for resources and to reproduce. Captive bettas do not have to worry about these things, so their dietary requirements will be less. High protein treats, such as freeze-dried and frozen diets, should be fed sparingly—no more than once or twice a week. If you are breeding your fish, they will have different dietary requirements.
How Often to Feed Your Betta Fish
Most tropical fish will spend their days foraging for food. They are not built to have large, infrequent meals, and bettas are no exception. It is best to feed your betta at least twice a day. If you have access to your aquarium throughout the day, three meals are also acceptable. Try to space them out equally. Remember, proper water temperature is critical to proper digestion and metabolism. Be sure to have a reliable heater and thermometer in your betta aquarium and check them daily.
If you will be away for more than a day, plan to feed your fish using a timed vacation feeder or a trusted fish sitter. You cannot fast bettas for more than a few days.
How to Avoid Overfeeding
Overfeeding in bettas leads to a large, distended abdomen (coelomic cavity). You can see symptoms of lethargy and dropsy (bloating) as the internal organs are damaged. Overfeeding can present signs similar to mycobacteria infection, or fish tuberculosis, so it is critical you get your fish diagnosed by your aquatic veterinarian in order to protect your own health. The sooner you notice your fish is getting too large, the more successful any treatments will be. If you wait too long, there is no treatment that can help your fish.
Overfeeding occurs in bettas that are fed too much food for their metabolism to digest. The main factor affecting metabolism is water temperature. Water that is too cold for your fish will significantly slow down its metabolism. Be sure to have a reliable thermometer on your aquarium and check it daily to ensure the water temperature is appropriate (77-80 degrees Fahrenheit) for your betta.
Pellet size varies among commercial diets, but as long as you stick to the amount of pellets equal to the size of the fish's eyeball per feeding, pellet size is irrelevant. Feeding your fish one big meal a day can easily lead to overfeeding. Smaller meals throughout the day are easier for your fish to consume and digest and keep your betta healthier.
James, Raja, and Kunchitham Sampath. "Effect of animal and plant protein diets on growth and fecundity in ornamental fish, Betta splendens (Regan)." (2003).
Roberts HE. Fundamentals of Ornamental Fish Health. Wiley; 2009.