Siamese fighting fish (Betta splendens)

Colourful bubble nest builders

Betta Splendens, commonly known as Siamese fighting fish or just Betta, are an aquarist favourite primarily for their extraordinary range and vibrancy of colour, but also for their fascinating ‘Bubble Nesting’. The male builds a floating nest of saliva bubbles where, should they find a mate, the fertilized eggs will be deposited.

Betta Splendens originate from South-East Asia, along with their close cousins, the Betta Imbellis, Betta Mahachaiensis and Betta Smaragdina. All betta are members of the Grourami family (Osphronemidae) and  remarkable for their labyrinth organ, a specialised adaptation to their respiratory system that has a similar function to human lungs and allows them to breathe air directly from the atmosphere; this is in addition to their gills which can take oxygen from water. This adaptation means the Betta can survive in oxygen poor water and gives them a natural advantage over fish relying on just their gills.

Betta Splendens variations

The Betta Splendens have been selectively bread for hundreds of years, this practice originally was intended to enhance their aggressive traits and engage in the now illegal, fish fighting competitions.  In modern times these fish have been sort after and selectively bred for their aesthetics and to develop a vast variety of colours and fin shapes. The most common are the Veiltail, known for its long veil-like fins, the Halfmoon, recognisable by its 180 degree tail fin and the Dumbo which sports extra-large pectoral fins which look like elephant ears.

Keeping Conditions

Male Betta Splendens are best kept alone due to their territorial and aggressive nature, only introduce a female should you be interested in the fish breeding. Be aware that Betta often mistake a potential mate for an adversary and quite commonly will attack, which can result in the death of one of the fish.

Female Betta are often kept in groups known as Sororities, but it is important to remember that they can be as aggressive as their male counterparts, so a heavily planted tank with many retreats and careful monitoring is essential for their wellbeing.

A male Betta building it’s bubble nest

Water, Planting and Decoration

Betta, unfortunately, have a reputation for being healthy and happy in the tiniest of aquarium due to the misconception that in the wild they live in shallow puddles. Although, their natural habitat does change, outside the dry season Betta enjoy a territory about three feet square and as such any Betta should be kept in as large a tank as possible, but avoiding anything below 40 litres, with a water temperature of at least 24oC.

A Betta’s natural habitat is a tangle of plants, and bettas feel much happier in planted aquariums where they can hide and periodically sit on the leaves. Betta spend most of their time at the top of the tank near the surface of the water, as such, the choice of substrate is less important but they really do enjoy floating plants as this can give them an anchor for their bubble nests.


Siamese fighting fish are primarily carnivores (meat-eaters). Therefore, they should mainly be fed special foods such as Tetra Betta. These foods contain ingredients that are based on the fishes’ natural diet, and their worm-like shape encourages appropriate feeding. For extra variety, Siamese fighting fish also enjoy natural foods such as Tetra Delica Bloodworms.