Halfmoon Betta Guide (Care, Diet, Tank Mates)

Halfmoon bettas are a popular type of betta fish defined by their half-moonshaped tail. They are just one variety of Siamese fighting fish, or Betta splendens, commonly known as bettas.

Bettas are visually striking fish that can be classified according to the pattern, color, or tail type. Our article will tell you more about their origins, history, and appearance. We also set out how to keep and care for your Halfmoon betta, what to feed them, which health and behavior issues to watch for, and much, much more.

About Halfmoon Bettas

Betta splendens were originally freshwater fish native to Southeast Asia (e.g., Thailand, Cambodia, Vietnam, etc..) but are now amongst the most popular and widely available aquarium species worldwide. The genetics of bettas indicate likely domestication by humans at least 1000 years ago, making them one of the longest domesticated fish.

The Halfmoon betta is distinguished by its long, rounded tail that expands to a 180-degree semi-circle when the fish is flaring its tail and fins for display or in distress. Not naturally found amongst wild betta, Halfmoon bettas exist in many different colors and patterns, including Mustard Gas and Samurai.

The bright colors, varied shape, relatively low cost, and easy maintenance of the halfmoon betta all make them an attractive choice for home aquaria. Despite a reputation for aggression, with the right care and attention, they can make excellent pets. Halfmoon bettas are consistently amongst the most popular betta fish, regardless of color.

History And Origins Of Bettas

Betta fish were initially collected from the wild and bred to increase their aggression, being used as subjects in gambling matches, similar to dogfighting or cockfighting.

Wild betta fish will fight only for minutes before one fish retreats. The heightened aggression bred into domestic betta means that they can fight for longer, and death is more likely. Winners are determined by the fish’s willingness to continue fighting.

The popularity of betta fights apparently attracted the attention of the King Rama III of Siam (1788-1851), who began to collect fighting fish himself. King Rama III later reportedly gifted several betta fish to the Danish scientist Theodore Cantor.

Bettas began to appear in France, Germany, and other European aquaria towards the end of the 19th century and were soon a popular ornamental fish variety. It appears that they first entered the USA and Australia in the early 20th century.

Today, their popularity in home aquaria means that bettas are abundant in captivity. In the wild, habitat destruction and pollution mean that Betta splendens are categorized by the IUCN as vulnerable.

What Do Halfmoon Bettas Look Like?

In the 20th century, some betta breeders began to move away from breeding purely for aggression and selecting instead for color, pattern, shape, and other ornamental qualities. The colorful and shapely Halfmoon betta we know today emerged from these modern breeding movements in the 1980s. Halfmoon bettas are available in all betta colors.  

Wild bettas normally show strong color only when disturbed or agitated, but breeders have made coloration permanent. A wide variety of hues breed true, with offspring always displaying the colors of their parents.


As with bettas in general, male Halfmoon bettas generally have brighter colors and distinctive fins. Varying color patterns can also be found in male Halfmoon bettas.

Betta colors arise from layers of pigment in their skin as well as the refraction of light within a layer of translucent cells. Moving from deepest layers to surface, pigment or color layers are red, yellow, black, iridescent blue/green, and a layer giving a metallic appearance. The colors from these combine to give a wide variety of betta fish colors, including amongst Halfmoon bettas.


Female Halfmoon bettas do not possess the long flowing tails and fins of the males and are normally more subdued in color with simpler features, although still appearing in a variety of colors.

How Do You Care For A Halfmoon Betta?

The care of Halfmoon betta fish is very similar to the care of other betta fish, but you should pay particular attention to the size and shape of your fish and adjust recommendations to fit your own fish. You will also find more detailed guidance on some areas (e.g., diet, water conditions, tank size) further down in the article.

Tank Environment

Getting the tank environment right for your Halfmoon betta is crucial. Water temperature, pH (acidity or alkalinity), and filtration are all important. You must learn the ideal parameters for each and how to achieve them.  

Bettas are intelligent and curious fish that require stimulation from their environment to avoid boredom, lethargy, and a weakened immune system. Wild bettas spend much of their time hiding to avoid predators. Placing plants, rocks, caves, and other ornaments in your fish tank can simulate the natural environment, creating hiding places and helping your Halfmoon betta feel more secure.

Similarly, a well-planned and stocked tank environment can help cater to the betta’s instinct to claim territory, possibly focused around a particular plant or rocky cave. As they can become highly aggressive toward trespass from other fish tank occupants, they will require a larger tank volume if housed with other fish.

Make sure that any rocks, plants, etc.. have smooth textures and edges to avoid any damage to the delicate fins and tails of your Halfmoon bettas. Floating plants and leaves also give males an anchor for building bubble nests for breeding.  

A blue or white aquarium LED light with an inbuilt timer can help set a daily routine for your Halfmoon betta, simulating day and night in the wild.

Tank Size

The ideal tank would be at least 5 gallons. However, bigger is always better.

And if they’re sharing a tank with other species, bettas will definitely require a tank volume of at least 45 liters (10 gallons).

A tank that is too small could cause stress, disease, and a shorter life expectancy.

Diet And Feeding

The ideal betta diet consists mostly of animal protein. Feeding should take place once a day to avoid the health risks of over-feeding.

Managing Aggression

Bettas are highly territorial, and Halfmoon bettas share this wider trait. Male Halfmoons are likely to attack one another if housed in the same tank. In a confined space, female bettas can also become territorial and behave aggressively towards one other.

Without enough tank, space to establish separate territories, or provision of some means of escape, one or both fish could die. Males may even respond aggressively to the sight of their own reflection, which could lead to stress in some fish if mirrors are placed in a tank.

What Are The Best Water Parameters For Halfmoon Bettas

As anabantids, bettas possess something called a labyrinth organ which allows them to come to the surface of the water and take a gulp of oxygen-rich air, rather than relying solely on gills to extract oxygen from water.

This labyrinth organ has helped bettas develop a reputation for being better able to survive than many other fish in water with low oxygen levels due to poor quality or varying temperatures. While bettas can survive, this does not mean that they will thrive in a poorly maintained aquarium.

Low water quality can make bettas and other tropical fish liable to depression and disease. For maximum health, growth, and lifespan in your Halfmoon betta, you should adjust the water parameters to suit their needs.   


Your Halfmoon betta is naturally a tropical fish and will prefer water temperatures of 24–28 °C (75–82 °F). They may survive at extremes of 13 °C (56 °F) up to 35 °C (95 °F), but colder water can weaken their immune system and make them vulnerable to disease.

Installing a reliable heater in your betta tank will ensure that water temperature is maintained in the ideal range.


The pH level of the water will also affect your Halfmoon betta. The ideal pH is a neutral level of 7.0. Slightly higher levels are tolerable but monitor and adjust regularly to keep your betta comfortable.  

Water Hardness

 Bettas prefer soft water similar to their natural environment. They can tolerate a wide range of General Hardness (GH), between 5 – 20 DH or 70-300 ppm, but very hard water is harmful.

Adding Indian Almond Leaves, alder cones, or demineralized or distilled water to your tank will all lower water hardness naturally.

Ammonia, Nitrites, Nitrates

One way or another, your fish tank needs to provide sufficient biological filtration to support your fish. Biological filtration establishes a regular cycling of your tank, breaking down waste (ammonia) and converting it first into nitrites, then down to nitrates. This keeps the water safe for your fish.

It may be possible to provide the right amount of biological filtration without the use of an artificial filter (e.g., with sufficient live aquatic plants, thorough cleaning, and regular water changes). But with a Halfmoon betta fish in an ideally sized tank, you may find it easier to maintain excellent water condition with the addition of a filter.  

The filter will remove debris and toxins (ammonia etc..), help to oxygenate the water through surface agitation, and provide a place for beneficial bacteria to grow. A fully cycled tank will have enough established bacteria to convert ammonia into nitrates after 24 hours but can take around a month to reach this level.

Adding a good quality water conditioner to your tank can also help to remove chloramine, chlorine, and other water contaminants which are bad for fish. Some also contain an Aloe vera mixture to replace a fish’s slime coat. 

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What Diet Should A Halfmoon Betta Have?

Bettas are naturally carnivorous. In the wild, they feed on insect larvae, zooplankton, and small crustaceans, etc. Your Halfmoon betta should therefore be fed mostly on animal proteins, whether flakes, pellets, or frozen foods. A healthy, varied diet may contain ants, soldier fly larvae, black worms, white worms, grindal worms, bloodworm, brine shrimp, daphnia, and others.

When choosing foods, do note that betta fish have short digestive tracts which are not adapted for the consumption of cereals (e.g., wheat, corn), often used as filler in commercial fish food. Bettas cannot be fed solely on plant material.

As a general rule, you should feed a betta at least once each day, providing only as much food as your fish can eat in 3–5 minutes. Remove all leftover food after the feeding period. Overfeeding could cause health problems, including obesity, constipation, and swim bladder disease. Too much food in the tank can also contaminate the water.

Bettas have been known to survive for two weeks without eating, but this is not ideal. After a stressful event (e.g., a move to a new tank or complete water change), it may be normal for your Halfmoon betta to have no appetite for a day or two.

How Can You Tell Your Halfmoon Betta Is Happy And Healthy

The best way to know if your Halfmoon betta is happy and healthy is to spend time watching it daily and making notes of any changes.


A healthy Halfmoon betta will have a bright, vibrant color.

 Physical Appearance

Healthy fish will appear smooth, clean, and without blemishes. Their tails and fins will not be drooping, ragged, or marked with lesions.


Healthy fish will move in smooth, gliding movements. If they are slower than usual, twitching or rubbing against objects, something might be wrong.


If your Halfmoon betta loses its appetite for more than a day or two, it might be ill or under stress.

How Long Do Halfmoon Bettas Live & How To Improve Their Lifespan

When kept in optimal conditions, bettas normally survive for 3-5 years in an aquarium and have been reported living up to 7-10 years. To improve your Halfmoon betta’s life expectancy, there are several factors to consider.


A richly varied protein-based diet will give your Halfmoon betta the nutrition it needs for a long lifespan. Do not provide too much plant matter and remove all excess food from the water.

Tank Size And Exercise

At least one study has found that bettas kept in larger tanks (at least several gallons) and provided with proper nutrition and “exercise” (they were “chased around” with a stick for a short period) lived over nine years. A control group in smaller containers, without “exercise”, lived shorter lives.

 Water Quality

A good quality tank filter, live aquatic plants, regular removal of debris, and use of water conditioner will ensure clean, pH and GH-balanced, well-oxygenated water which is comfortable for your Halfmoon betta to live in.

Tank Environment

Add in a water heater to maintain ideal temperature, regular lighting, and suitable tank furniture (and compatible potential tank mates), and you have created a physically comfortable and low-stress environment where your Halfmoon betta can thrive and enjoy a long life.      

What Size Tank Do Halfmoon Bettas Need?

In general, a betta fish tank should be no smaller than 19 liters (5 US gallons).

Long-tailed Halfmoon bettas may be slower moving and have more difficulty maneuvering in the water than shorter-tailed and shorter-finned Halfmoon bettas. Being less active, they may adapt better to a slightly smaller tank than shorter-tailed Halfmoon bettas, which should be housed towards the upper end of the scale above.

What Are Common Diseases That Affect Halfmoon Bettas?

All tropical fish living in captivity are susceptible to certain diseases which may arise from bacterial, fungal, or parasitic infections. Illnesses are far more common in fish living with poor water quality and lower temperatures than recommended, both of which can weaken the fish’s immune system.

The four most common betta diseases are dropsy, white spot, velvet, and fin rot. Apart from dropsy, all can be successfully treated with over-the-counter fish medication, increased water temperature, and/or regular changes of water.


Dropsy, or edema, is a condition in fish involving swelling of soft tissues in the abdomen or other body cavity due to an accumulation of fluid. As the infection progresses, skin lesions may appear, internal organs are damaged, and the mortality rate is high, even with treatment.

It is normally a disease of fish with impaired immunity, caused by an infection of Aeromonas bacteria, commonly present in aquarium habitats. Healthy fish may be exposed to dropsy-causing bacteria without falling ill.

Treatment has the greatest chance of success when started early. It could involve moving the affected fish to a “hospital tank” with clean water, 1tsp of salt per gallon of water, and some high-quality food. A broad-spectrum antibiotic may be administered in food or water in accordance with the manufacturer’s directions.

Prevention is better than cure, so avoid dropsy by monitoring and caring for your fish appropriately. If your Halfmoon betta’s immune system is compromised by low tank temperature, poor water condition, or some other stress factor, they may develop dropsy.  

White Spot

White spot, also known as ‘ick’ or ‘ich’ is caused by the external parasite Ichthyophthirius multifiliis, which latches onto fish and makes their skin itchy and uncomfortable. The key visible symptoms are white spots or sores where a fish has attempted to rub affected skin on objects for relief.

When suffering from white spot, your Halfmoon betta may become lethargic, even more reclusive, lose appetite, clamp their fins, or suffer breathing distress.

The parasite which causes white spot is present in most aquaria but does not affect healthy fish whose immune systems are strong enough to fight it off. White spot indicates a compromised immune system caused by environmental or other stresses.

There are several treatment options for white spot involving changing the temperature and salinity in the tank, moving the fish to a different tank until the parasite dies, or treating the fish with medication containing methylene blue or malachite green.  


Also known as Rust, Gold Dust Disease, or Coral Disease, velvet makes your fish look like it is covered in gold dust or rust. It is caused by the Oödinium parasite, and the gold coating is a result of your fish producing excess mucus in order to fight the infection.

In the early stages of velvet, you may observe your Halfmoon betta twitching and rubbing itself on objects in an attempt to relieve irritation. They may become lethargic and lose appetite. In the later stages of the disease, your fish’s eyes may bulge and cloud over, there may be visible lesions or ulcers on their skin, and they may clamp their fins close to their body.

You can treat velvet using similar temperature, salinity, and medication regimens to those for white spot but tailored to target the Oödinium parasite.  

Risk factors for velvet include lowered immune system, old tank water, and adding new fish or to your tank without quarantining them for four weeks first. New plants could also carry the parasite and should be thoroughly disinfected before being placed in the tank.   

Fin Rot

Fin rot or tail rot is the most common infection amongst betta fish in aquaria. It is normally caused by a gram-negative bacterial infection (e.g., Pseudomonas fluorescens) or fungal infection and will affect stressed fish with compromised immune systems rather than healthy fish. With timely treatment, the prognosis is good, and full recovery is likely.

In bettas, fin rot is generally caused by poor water conditions, with tank water being too cold (under 78F), cloudy, and contaminated with old food particles and feces, which raise ammonia, nitrite, and nitrate levels. Overcrowding caused by too many fish in one tank can rapidly reduce water quality and lead to fin rot.

Another underlying cause may be inconsistent feeding, with overfeeding or underfeeding damaging immune health.

Symptoms of fin rot vary across mild to severe stages, starting with brownish or jagged fin edges and white tips or spots, and progressing to red, inflamed, or bloody fin bases, or even complete loss of fin and fin membrane.

Fin rot should not be confused with tail biting and fin nipping injuries or snags from rough tank decorations. Rips and tears will not normally have brown or black edges and will not be associated with other symptoms of disease. (NB Some breeds of betta fish like the double tail Halfmoon are bred to have split fins.)  

Treatment recommendations vary depending on the stage and progression of fin rot in your fish.

The tank size and its full ecosystem, including other fish in the tank community, are also relevant. Consult detailed guidance on treatment and to prevent a recurrence, make sure you are keeping your tank water clean, well-heated, and not overcrowded.

How Do You Breed Halfmoon Bettas?

Natural aggression means that Halfmoon betta fish can be challenging to breed. Breeding should always be undertaken with caution and supervision.

Bettas are bubble-nesting fish where males are responsible for building nests of bubbles, courting females, defending their territory around the bubble nest, and caring for the eggs and hatchlings.

Betta bubble nests are constructed from saliva-coated air bubbles. During the bubble nest phase, male aggression toward females is lowered as they attempt to attract potential mates.

Males express interest in a female by flaring their gills, spreading their fins, and twisting their bodies. Receptive females respond by darkening in color and developing lines known as “breeding bars”. In spawning, the male betta wraps his body around the female in a “nuptial embrace” until the female has released all her eggs, which the male will cover in milt (seminal fluid).

 At this point, the male will chase the female from his territory to prevent her from eating the eggs. In an aquarium situation, the female should be removed from the tank to prevent injury or death.

What Tank Mates Can Live With Halfmoon Bettas

Although male bettas are normally solitary and aggressive towards one another, they can still inhabit a tank with many types of fish if there is adequate space and suitable hiding places. Broadly speaking, tankmates for your Halfmoon betta must be tropical fish, communal, nonterritorial, and possess a different body type without long flowing fins.

Female bettas are less aggressive and territorial than males, generally making them suitable tankmates for a wider variety of fish. They can also tolerate larger or more numerous tankmates. Male and female bettas should not be kept together, except temporarily for breeding purposes.

Potential tankmates should generally be put in the tank before your Halfmoon betta so that they can establish their territory beforehand and avoid competing with the betta.

Coldwater fish (e.g., goldfish) are incompatible tankmates for betta fish due to different water temperature requirements. Aggressive or predatory fish should be avoided as they are likely to nip the betta’s fins or damage their slime coat. Brightly-colored fish with large fins, especially if smaller and slower (e.g., male guppies), are also unsuitable, as they may be attacked by the male betta.

Compatibility with tankmates will also vary with the temperament of your particular Halfmoon betta, whether male or female. You should carefully supervise the betta’s interaction with any other fish, especially in the early days of sharing a tank.

Tetra Fish

Species that shoal, including Tetra fish, usually keep to themselves and can endure the territorial nature of bettas with their numbers.

Danio Fish

Another shoaling species, Danio fish varieties can also cope well with sharing a tank with Halfmoon bettas.

Kuhli Loaches

These eel-like scavenger fish are a good tankmate who will pick up any excess food your betta drops. As nocturnal creatures, they often hide together during the day and then become more active at night when your betta is sleeping, minimizing the potential for aggressive interactions.

Cory Catfish

Corydoras or Cory Catfish are schooling fish that prefers to dwell at the bottom of the aquarium, slightly out of the betta fish’s space.


How Much Do Halfmoons Cost

The popularity of the Halfmoon betta fish means that it is relatively cheap and easily available in most countries. While aquarium and pet shop sites list male and female Halfmoon bettas for less than $15 and as low as $3.50, you should also factor in the costs of care and upkeep of your fish.  

The initial outlay for a tank and outfitting may be $205 – 345. Annual expenses, including electricity, food, and water conditioner, could be around $80 – 110.

Are Halfmoon Bettas Aggressive?

Yes, Halfmoon bettas are aggressive, being descended from fish originally bred for fighting ability. You should take this behavioral trait into consideration when thinking about tankmates or breeding.

Can You Put Halfmoon Bettas Together?

You should only put Halfmoon bettas together in a tank large enough for them to establish their own territories, and ideally with some means of escape.

How Big Do Halfmoon Bettas Get?

Long-tailed Halfmoon bettas generally reach a little over 3 inches, with their tail length included. Hybrid species may be longer.

Can Halfmoon Bettas Jump

Some bettas can jump! Plakat bettas are known for trying to jump out of their aquarium…  

Are Doubletail Halfmoon Bettas Rare?

Double tail bettas have two distinct tails due to a genetic mutation, which means that their caudal fins are separated at the base and grow in two lobes. The double tail Halfmoon betta is rare due to a low survival rate amongst its offspring.


Halfmoon bettas are betta fish that have a tail capable of spreading exactly 180 degrees. They come in all betta fish colors and in both a short-tailed and long-tailed form. With the right conditions and the right care, your Halfmoon betta can enjoy a long, healthy, and happy life for many years to come.

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