Siamese Fighting Fish (Betta) This article is verified by a vet

iridescent blue betta fish in aquarium

The noble Siamese fighting fish is one of the most splendid ornamental fish for aquariums.

Radiantly colourful and somewhat aggressive towards other fish and conspecifics: The Siamese Fighting Fish is a remarkable creature that brings a dash of colour to any aquarium. With modest demands, this pet is incredibly easy to care for and very popular with aquaristics beginners. This article compiles the most important information about the Siamese Fighting Fish.

Profile: Siamese Fighting Fish

  • Other Names: Betta; Siamese Fighting Fish (Betta splendens)
  • Size: Depending on the subspecies, 4-16cm
  • Keeping: Maximum 1 male, up to 3 females, aggressive territorial fights possible
  • Tankmates: Possible only with a few species (e.g., bottom dwellers)
  • Aquarium: Freshwater, at least 54L
  • Water Temperature: 24-30°C
  • Water Hardness: 10-25° dGH, pH level between 5.0-8.0
  • Food: Carnivorous, frozen and live food
  • Difficulty Level: Beginner

Appearance: Colourful, Iridescent and Diverse

While the true wild form of the Siamese Fighting Fish is rare to found, its cultivated forms flaunt an array of colours. They are available with long, fluttery fins in numerous hues.

Particularly noteworthy is its labyrinth organ, which enables the fish to absorb oxygen even in oxygen-poor freshwater environments.

How do you recognize female Siamese Fighting Fish?

While males are very colourful, females tend to have more muted colours. Both sexes reach a size of about four to 16 centimetres.

What varieties are there?

Biologists categorize the Siamese Fighting Fish into many subspecies, depending on patterns and forms. The classification includes eight main pattern groups, which primarily describe the marking and colouring of scales and fins:

  • Akarensis
  • Antonii
  • Aurigans
  • Balunga
  • Chini
  • Ibanorum
  • Pinguis
  • Obsura

In addition to the patterning, classification also includes tail shape:

  • Crown Tails display a colourful fin.
  • Halfmoons have a crescent-shaped fin, which come in many colours.
  • Long Tail Bettas are identified by a long tail fin and an extra-large fin on the belly side.
  • You’ll also find Siamese Fighting Fish with veil tails, round tails, delta-shaped fins, or double tails.

However, the majority of Bettas available in pet shops have the distinctive veil tail, with either rectangular or diamond-shaped cuts.

Red Betta fish swimming through aquarium foliage © Chonlasub / stock.adobe.com
Blue, red, yellow – you can find Siamese fighting fish in almost every colour. You can also come across black or white specimens.

Keeping: How to keep Siamese Fighting Fish correctly?

Caring for a Siamese Fighting Fish is straightforward, making it suitable for beginners. Since this colourful fish is relatively small, you need not invest in a very large aquarium.

The aquarium and water should exhibit the following features:

  • Size: 60 cm
  • Volume: 54L (30L is sufficient for smaller nano Siamese Fighting Fish)
  • pH Value: 5-8
  • Temperature: 24-30°C
  • Water Hardness: 10-25° dGH

What temperature do Siamese Fighting Fish need? 

Due to its large fins, the Siamese Fighting Fish requires plenty of energy and space to move around in the water. The ideal temperature is between 24 and 30 degrees Celsius. 

Temperatures below 20 degrees Celsius can cause discomfort to the fish; they will likely be less active. You can gently heat the water in a 30L aquarium with a 25-watt heater. 

Siamese Fighting Fish do not appreciate fast-flowing water; they prefer still waters like in their natural habitat. Consider this when setting up your aquarium. 

What plants are suitable for Siamese Fighting Fish?

Siamese Fighting Fish adore aquatic plants planted at the bottom of the tank. Generally, Asian plants are preferred over European aquarium plants. 

They enjoy densely planted areas and smaller floating plants, although space should still be left on the water’s surface for bubble nests. 

Although dense plant cover will make the tank appear darker, the fish feel comfortable in this atmosphere. Red-green and white-green marsh plants also provide optimal shade. 

The right decoration 

For decoration, you can use real stones and wood. You can choose these elements according to your preference, as long as you do not use bright or coloured stones. Whether gravel, rounded pebbles or sand – the choice is yours. 

Are Siamese Fighting Fish loners? 

While there are peaceful individuals, the Siamese Fighting Fish can sometimes be unfriendly. They can be very aggressive, which is why you should never house two males together. It is therefore advisable to keep male specimens alone. 

What fish can be kept with a Siamese Fighting Fish? 

With other fish species, it’s important that they are neither too large nor too small. Larger fish may see your Siamese Fighting Fish as prey, while smaller fish might become prey themselves. 

Cichlids exhibit similar territorial behaviour, so they’re not great candidates for cohabitation. Guppies are a definite no-go. Danios are not suitable either, as their high activity levels can stress out your Siamese Fighting Fish. 

The best tank-mates are catfish and fish of similar size with small fins. 

Care: Cleaning the aquarium

For hygiene reasons, you should always remove food remnants, waste and dirt from the substrate. If not, disease-causing organisms can multiply, leading to serious infections.

The water quality will also suffer if you don’t clean the tank occasionally, impacting the health of your fish.

How often should you change the water for a Siamese Fighting Fish?

Regular water changes (about once a week) can negate the need for a filter. However, small internal filters have their advantages; they’re quiet and usually adjustable.

You might also consider using water conditioners, as these clean the water of any possible heavy metals. However, too much can destroy important bacteria that fish need from time to time.

Feeding: What can Siamese Fighting Fish eat?

Free-living Siamese Fighting Fish predominantly feed on small soft-bodied animals and insects. Siamese Fighting Fish kept in aquariums are strictly carnivorous. Plant-based fish food is therefore not an option.

You can also purchase special flake food and granules. These should contain ample animal protein, which the fish need for muscle building. Alternatively, you can feed them live food (such as flies, larvae, or mosquitoes).

Many Siamese Fighting Fish owners also offer frozen insects. Small portions of green beans are also generally acceptable.

How often should you feed a Siamese Fighting Fish?

A Siamese Fighting Fish should be fed regularly. Ideally, feed it once every day.

Health: How long does a Siamese Fighting Fish live in an aquarium?

With an average lifespan of about three to five years, Siamese Fighting Fish do not live very long but are generally healthy and robust fish. Failure to follow recommendations for care and feeding can, however, lead to illness in your fish.

A significant threat includes fungal and bacterial infections. These can be due to underpowered filters. On the other hand, filters can also cause stress, which may lead to diseases and death.

Recognizing early signs of illness

Sound the alarm if your fish is lethargic and stays at the bottom of its tank. This could be a sign that it is ill or stressed. It might also indicate that the water temperature is too low.

If your fish exhibits swollen eyes, half-open gills or other pathological changes, you should seek advice from your vet. You should also isolate sick animals from others.

In contrast, a healthy Betta Fish regularly swims through its territory. It carries its tail and fins stretched out far from its body. Its scales smooth and clean.

What diseases are common?

Siamese Fighting Fish can suffer from various fish diseases. For example:

  • Dropsy: Your fish’s scales protrude widely from its body, leading to a pinecone-like appearance. This can be caused by poor water quality, lack of hygiene, and incorrect feeding.
  • Fin Rot: This disease causes your Betta’s fins to fray and appear milky. Here again, poor hygiene, especially following an injury, plays a significant role.
  • Pop-eye or exophthalmia: The eyes of your fish swell significantly. At the same time, a milky-looking layer forms over the eyes. Possible reasons include injuries and bacterial infections.
  • Scale Protrusion: Commonly, the scales stand out on the flanks as well as on the head and neck. Your fish may have been injured, allowing bacteria into the wound. Parasites could also be the cause.

Behaviour: Is the Siamese Fighting Fish dangerous? 

The name Siamese Fighting Fish (scientifically Betta) is not without reason. While Siamese Fighting Fish are not dangerous to humans, they are highly aggressive towards other fish and species.

In Thailand, people even hold competitions where aggressive fish fight each other. Such betting contests traditionally do not occur in Europe or America. Instead, they are a popular pet, mainly due to their splendid appearance.

Which Siamese Fighting Fish are peaceful?

There are exceptions to every rule. For example, Betta imbellis, also known as the Peaceful Fighting Fish, is a cheerful companion.

Origin: Thailand – The Home of the Betta

Thailand is internationally recognized as the home of the Siamese Fighting Fish, mainly due to the traditional fish fights.

However, the term “Betta” indicates that the Siamese Fighting Fish, also known as Betta splendens, is spread elsewhere too.

The word Betta originates from Javanese (Java, Indonesia). In Thai, the fish is more commonly known as Pla-kad or Trey Krem.

The fish species native to Southeast Asia prefers the freshwater bodies of Indonesia and regions around Bali, Malaysia, Laos, Vietnam, Myanmar and Cambodia. Outside Southeast Asia, Siamese Fighting Fish are found only in aquariums or private ponds.

Blue-Red Siamese Fighting Fish exploring aquarium floor © lalalululala / stock.adobe.com
Betta fish prefer a dark substrate.

Buying: What you should consider when getting a Siamese Fighting Fish

Siamese Fighting Fish are a true classic in pet shops. Often, you’ll find only common varieties with Crown and Halfmoon Tails. To find more unique breeds, you may need to place special orders or look in larger cities.

Another option is the Internet, which offers a very wide selection of Bettas. You can browse at your leisure but will usually need to pick up the animals in person.

How much does a Siamese Fighting Fish cost?

A standard specimen may cost around £10 to £20. However, the price varies depending on species, origin, and appearance. Therefore, more popular examples can cost well over £100 each.

Conclusion: Are Siamese Fighting Fish suitable for beginners?

Siamese Fighting Fish are suitable for aquaristics novices. It’s crucial that you follow the recommended guidelines for proper care and feeding of your fish. By doing so, you can enjoy the vibrant and delightful company of these fishes in your aquarium for a long time.

Do you have pets at home? Here are some purchase proposals curated by the zooplus editorial team

The products featured have been carefully selected by our editorial staff and are available at the zooplus online pet shop. The selection does not constitute advertising for the mentioned brands.


Franziska G., Veterinarian
Profilbild von Tierärztin Franziska Gütgeman mit Hund

At the Justus-Liebig-University of Giessen I was extensively trained as a veterinarian and was able to gain experience in various fields such as small animal, large animal and exotic animal medicine as well as pharmacology, pathology and food hygiene. Since then, I have been working not only as a veterinary author, but also on my scientifically driven dissertation. My goal is to better protect animals from pathogenic bacterial organisms in the future. Besides my veterinary knowledge, I also share my own experiences as a happy dog owner and can thus understand and enlighten fears and problems as well as other important questions about animal health.


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