Why Is My Betta Fish Not Eating? (Checklist & Solutions)

Betta fish are normally eager eaters and don’t need encouragement to fill their bellies. In fact, overfeeding is usually a bigger concern because a betta can usually eat far beyond what it needs to survive.

But what if your betta fish starts to slow down or even stop eating?

A lack of appetite is often the first sign that something is amiss in your aquarium. While it’s a very general sign, it’s also a clue that invites you to look more deeply into how you’re caring for your fish.

Causes of a betta fish not eating can include anything from simple temperature issues to more serious conditions. If your Betta fish starts refusing food, here are some tips to consider that should help set things right again.

betta fish eating

Consider the Water Quality in Your Betta’s Tank

One of the most common reasons bettas and other fish refuse to eat is because the water conditions are poor. If you aren’t performing regular water changes, the aquarium hasn’t fully cycled, or you don’t keep a filter running, toxic compounds can build up to stressful levels.

The most common toxins found in aquarium water are ammonia, nitrite, and nitrate, which are toxic to varying degrees. Each can be lethal as their concentration rises – ammonia being the most toxic nitrogenous waste product and nitrate being the least toxic and very well tolerated by betta fish.

Since concentrations can sometimes change from healthy to dangerous in a few hours, you should always keep aquarium water test kits or strips on hand to monitor conditions when your betta fish stops eating.

Most kits carry ammonia strips separately as the chemical reagents are reactive towards the ones that come with the 5-in-1 sets. But I recommend using liquid test kits most of the time. While they are less convenient and a little pricier they give much more precise results than color matching paper strips, which are very vague.

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Sudden shifts of healthy parameters can also cause a betta fish to not eat while its body adjusts to the new conditions. pH swings can be very stressful to fish and are easily underestimated by new aquarists because the scale of pH isn’t linear, it’s logarithmic, using powers of ten.

Essentially, this means that the difference between 1 degree of pH (i.e. 5.0-6.0) is a tenfold decrease in the acidity of the tank! And two steps along the scale represents a hundredfold change in the acidity or alkalinity of your water, something that a test kit doesn’t quite help you realize.

Betta fish actually prefer acidic conditions (pH 5.0-7.0) but will still do well in alkaline water (pH 7.0+) as well. But it’s worth remembering that tap water in most countries is neutral to strongly alkaline in chemistry.

For example, many aquarists use Indian Almond leaves in betta tanks in order to add tannins and lower the acidity. But if you’ve performed a major water change using alkaline tap water, you’ve just swung the pH drastically in the other direction. Bettas are very tough and this won’t likely kill one. But it is certainly enough to cause it to stop eating until its body adjusts to the pH swing.

Symptoms of Poor Water Quality

Signs of ammonia, nitrite, and nitrate poisoning include more than simply not eating. Your betta fish may also become listless, show gill discoloration or even bleeding, especially in the fin rays and blood vessels. You may see your betta fish laying at the top or bottom of the tank, with ragged fin edges, and gasping.

Nitrate poisoning is the most likely of the three because it’s the least fatal and can be tolerated for a longer period. Bettas with nitrate poisoning will show brown gills because the nitrate is starting to displace the hemoglobin in their blood. This would normally be fatal within hours for most fish – but the labyrinth organ bettas have enables them to breathe atmospheric air and keeps them from suffocating.

The nitrates accumulated in their blood still causes them stress, so you’ll need to perform heavy water changes (~50%) and clean out your filter in order to save them. Once nitrate levels diminish to a safe level (15 parts per million or less), your betta fish will eventually start eating again!

Ammonia and nitrite have much lower safe levels than nitrate. But the cure for toxicity is also the same: you need to perform a large, immediate water change to purge the system of nitrogenous waste!

pH swings don’t have immediate symptoms you can see beyond lethargy, clamped fins, and a lack of appetite. Your betta fish will eventually perk back up; just be aware of how your water chemistry fluctuates and adjust incoming water to avoid these swings in the future!

Baby betta fish eating live food
Baby betta fish eating live food

How is the Temperature?

Bettas are some of the hardiest tropical fish around and can survive in extremes that would kill other fish. But as Southeast Asian natives they still prefer warm, heated water (75-84F). They tolerate room temperature conditions but become significantly stressed when the temperatures drop below 70F for an extended period of time.

Bettas are cold blooded animals, which means that their metabolism slows in cooler environments. Heart rate, nerve impulses, cell division, and digestion all slow down. They eat less food but also have a reduced growth and immune response, making them vulnerable to digestive issues and infections.

Symptoms of Conditions that are Too Cold

A betta that is too cold will likely hang limply near the surface or the bottom. It won’t spend much of its time exploring its environment because it needs to conserve energy. A cold betta will generally eat once per day but won’t have the continual pigginess that a betta kept in a warm environment will display.

A simple aquarium thermometer gives you a constant reading on where you stand and whether you should invest in a heater or not! Just be careful to choose a heater with the right wattage since a heater that’s too strong can overheat the small 1 to 5 gallon tanks commonly used as betta quarters. A strong heater can even burn a fish that comes into close contact with it.

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Heaters are actually a complex topic that I have gone into great detail discussing. If you have a larger aquarium in need of heating, take a look at this article on the best aquarium heaters on the market.

Are You Trying to Feed Your Betta Fish Too Often?

Could it be that your betta isn’t eating because he’s already full? Bettas are aggressive eaters but they don’t need nearly as much food as their eager wiggling might suggest. They don’t have strong currents to work against in most aquariums, several rivals to fend off, or crowds of females to impress. In short, they’re basically couch potatoes in their nano tank.

Signs That Your Betta Fish Is Already Full

A full betta isn’t as easy to recognize since they tend to be somewhat plump at all times.

As a rough rule of thumb a Betta’s stomach when full is about the size of an eye. Feeding beyond this is too much and will be uneaten, partially digested, or simply lead to fat. If his stomach is swollen without scales disdenging in an unnatural way, your betta simply doesn’t need to eat.

Observation is the key to success here! You should get used to watching your betta eat during each feeding so you know precisely how much he needs. It’s when aquarists feed and then step away that people suddenly have to wonder just how much their fish eat.

So when you first offer food, try offering just a few pellets rather than the entire meal all at once. If your betta has a lackluster response then he’s likely full and doesn’t need any more pellets added to the tank.

Being cautious when feeding has the added advantage of ensuring your leftover food isn’t going to rot. Rotting food is a major source of ammonia, which can lead to ammonia poisoning (see above). If you have a small net on hand, you might even remove leftover flakes or pellets for this reason.

Are You Offering New Food to Your Betta Fish?

Bettas are usually eager eaters that will snap at the first thing that hits the water! But sometimes they can be notoriously picky. This is very common if you’ve trained your betta to eat just a single kind of prepared food for years. If you’ve given your betta a single brand of flakes for ages, a sudden switch to pellets can be jarring to them.

Bettas can also be spoiled by long exposure to rich delights like Tubifex worms. These are the most common foods for a betta to become “addicted” to because they are rich in fat and protein. Tubifex are sometimes eaten with so much relish that your betta may ignore standard fare for a few days once the worm buffet is over! The high fat content will also tide them over, dulling their appetite.

While I always recommend offering live and frozen foods to balance out the missing nutrients from a prepared blend, it’s good to never stick to one item for too long. Treats are always good but remember to mix things up. This is the best approach to not only a balanced diet, but good color, and optimal health for your betta!

Signs Your Betta Fish Doesn’t Recognize a New Diet

A betta that simply doesn’t recognize a new food item will often dash to investigate what you’ve added to the tank. He will then study it intently as bettas have excellent vision for picking out prey trapped near the surface. He may take an investigative bite, only to then spit the pellet back out. If he does this a few times in a row, it’s likely that the formula tastes strange or the consistency is wrong.

Bettas that have been fed soft items like frozen food and flakes, only to switch to hard pellets often display this behavior. The pellet smells and tastes right but the consistency throws them off. Imagine eating pancakes and omelettes forever, only to have stale, hard biscuits offered to you one day!

Since new betta may be more accustomed to soft pellets, thawed frozen foods, or other “luxury” fare, I recommend offering your fish these items for the first few days. The stress of a new environment can also depress his feeding response even further, so be patient.

He may snub hard pellets or a strange tasting flake food blend the first few times. But a healthy betta will rarely ignore food for more than a couple of days. If he continues his fast then it’s more likely that there is some other underlying problem, such as a disease or poor water quality.

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You can also try pre soaking hard pellets. This makes them softer and more palatable for a picky betta. I recommend pre soaking them in garlic extract, which is fortified with vitamins to boost the nutritional content and makes them far more appealing to their sense of smell and taste! And just as in humans, garlic boosts disease resistance in bettas and other aquarium fish!

Is Your Betta Fish Showing Signs of Disease?

Disease symptoms can go unnoticed for days or weeks if you’re busy. Which is unfortunate because even diseases that are normally fatal can be checked if caught early enough. A slowing or complete halt to eating is often the very first clue you have before other symptoms show up.

If you notice your betta fish not eating, check him carefully for torn fins, discolored patches of skin, pale coloration, fuzzy growths, swellings, and other abnormalities. Distended scales, cloudy eyes, small wounds…Anything that looks out of the ordinary

The long fins of bettas are especially prone to fin rot and need treatment quickly as the disease can be lethal. Unnoticed injuries combined with poor water quality lead to the perfect conditions for disease to set in.

Dropsy (fluid bloat) and Popeye are also common Betta diseases caused by internal bacterial infections. Like fin rot they are treatable if caught early!

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Lastly, a dash of aquarium salt is always a good idea for listless fish. Salt helps regulate gill function and ion exchange between fish and their environment. It also stimulates the slime coat, which is essential to disease resistance.

Common Betta Fish Diseases to Look Out For

Common betta diseases to watch out for include not only fin rot but ich and body fungus. Ich shows up as a dusting of salt like white specks across their skin. Ich is actually a contagious parasite and you’ll need a copper-based medication to kill it.

A betta with ich will often stop eating and spends a lot of time scratching against the gravel, plants, and other surfaces. Fortunately, if you catch it early enough, ich is rarely fatal.

Fin rot and body fungus can be more dangerous. These diseases take an open wound to get established. But the main cause is dirty water where bacterial and fungal spores can accumulate to infectious levels.

A betta with a fungal disease also has a depressed immune system to begin with, probably due to high levels of ammonia or nitrate. So treat your betta with an antifungal remedy – but also perform regular water changes to flush out the infectious spores from your tank!

Summary

As you can now see, there are many potential causes of your betta fish not eating. Water quality and cold temperatures are the first things I look out for. But it’s also possible that your betta may be a picky eater, or worse, sick with a disease that needs medicating.

Sometimes your betta is simply refusing to eat for mysterious reasons. If none of the above cases apply you’ll almost certainly see your fish start eating again in hours to days, with no intervention required by you.

And even if there is an issue to address, bettas tend to bounce back within hours or days once you find and correct the cause for their reluctant appetites! Their natural hardiness is as much a reason for their popularity as their beauty. So take the time to carefully examine your betta and let me know how things go below!

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