Betta Smaragdina | Complete Guide to Keeping Them

betta smaragdina guide
Table of Contents

If you are interested in fish keeping and plan to start raising fish of the Betta Smaradina species, there are a few things to know and note before you get started. Raising and taking care of this fish species requires some research to give them the optimal environment and conditions that will help you along the way.

Credits: Iven Betta

Common names for Betta Smaragdina

The common names for the Betta smaragdina are blue betta, emerald betta, emerald green betta, Mekong fighting fish, and peaceful betta. 

Where can Betta Smaragdina be found?

Betta smaragdina is a species of fish that is native to the region of Eastern Thailand.

Species Localities of the Betta Smaragdina

You can find them mainly in the Mekong River and Chao Phraya basin. They have also been found in the rivers in central Laos and some parts of Cambodia.

In the most recent discoveries, the Betta smaragdina were found in Western parts of Thailand in the Kanchanaburi province.

Habitat of Betta Smaragdina

You can usually find the species of Betta smaragdina in stagnant waters, swamps, and rice fields. Most common places where they stay have low dissolved oxygen with minimal vegetation. 

However, they have also been found in ponds and ditches with slow-moving waters. The substrates are usually sandy or muddy in the areas depending on where they are found.

How to take care of Betta Smaragdina

Betta smaragdina can live better in conditions where it is shaded and with sufficient underwater vegetation. The forms of vegetation can be stem plants, epiphytes, and other greeneries where the fishes can find a place to retreat as a form of shelter. 

Tank Size for Betta Smaragdina

A great aquarium size for these fishes to live comfortably should measure at least 45 x 30 centimetres (1.5ft x 1ft). This sizing should be able to house a pair with ease.

Aquarium layout for Betta Smaragdina

The aquarium should have adequate spacing so that the fishes can have sufficient refuge and hiding spaces all over the tank. Try spreading out roots, stems, and branches so that it is similar to their natural habitat.

You can also place rocks, unused pots, and other materials for alternate forms of shelter as long as the fishes can fit in them. Placing additional dried leaves and branches can also serve as a platform for other microbes, further becoming a secondary source of food for the fishes and fry. 

For substrate, you can use an inert light brown sand or dark aquasoil. The former replicates the natural habitat while dark aquasoil brings out its natural colours while reducing the pH of your aquarium

As these species live in stagnant natural water, there should not be excess water movement in the tanks. Also, do not fill the tank up to the brim, as the fishes need a certain level of humidity on the water’s surface. 

Water conditions for Betta Smaragdina

Since the species of Betta smaragdina are very tolerant to any type of water chemistry, there is not much emphasis on maintaining water conditions. However, you should still keep it clean and try to mimic their natural water composition.

The temperatures should measure around 22-28C or 72-73F, and the pH levels should measure from 5.5-7.5. 

The dissolved magnesium and calcium, which translates to ‘hardness’ of the water, should be around 18-179 ppm. 

What can be kept with Betta Smaragdina?

Generally, it’s not recommended to put them in a community tank, as they can be territorial and aggressive to other fishes. They thrive better when they are left alone. 

But if you would like to try, you can try placing peaceful cyprinids, loaches, and snails. However, do separate them during the breeding process.

Feeding Betta Smaragdina

Betta smaragdina feed on aquatic and micro vertebrae found in their natural habitats in the wild. The fishes in the tank will feed on dried food products once recognised as food. In fact, species in the splenden complex are pretty easy to train onto pellets.

You should also make it a point to feed them with live and frozen foods to fully develop their colours and form. Since it is very much possible for them to become obese, make sure not to over-feed them. Keep and maintain regular feeding schedules.

Read my betta feeding guide here.

Sexing Betta Smaragdina

betta smaragdina emerald
Credits: Iven Betta

Males tend to show stronger shades of hue and colour on their scales and also have longer fins. The females will look more brownish with shorter fins, where they also display an egg tube. 

Breeding Betta Smaragdina

Betta smaragdina species are bubblenesters. So you must provide a spawning area via the use of floating tubes and canisters for their nests. Alternatively, floating plants or a styrofoam cup cut in half can do the job as well.

The breeding pair does not need to be separated before spawning. Make sure to condition the pair before spawning properly. 

The male gets to work by building a nest in the tubes or canister that you provide.

The female will develop darker shades on her sides. Once the pair is ready, the male will wrap himself around the female, after which the spawning will take place. 

The eggs are then released so that the female can catch them under its fins. Then the male will move the eggs to the nest repeatedly until the female runs out of eggs. The hatching of the eggs occurs in 1 to 2 days, where nesting will take place for 3 to 4 days. 

The fry then comes out to swim around once they are fully capable of doing so. 

The fry also needs a level of humid air to develop its internal organs fully. Feed them with small food like microworms and daphnia for the first 2 weeks before feeding them with baby brine shrimp. Make sure not to overfeed them to avoid health issues.

Standard length of Betta Smaragdina

The Betta smaragdina species have a standard length of 5 to 6cm or 2 to 2.4 inches. 

Lifespan of Betta Smaragdina

It’s been said that the Betta smaragdina can live between 5-7 years, but I’m more inclined to believe that its lifespan will be between 2-4 years, typical of Bettas.

Similar Species

Similar species to the Betta smaragdina are those in the Betta splendens complex. However, Betta smaragdina can be identified by their primarily blue/green/emerald colouration with red or brown membranes on their fins.

They also have blue/green/emerald operculum bars (near their gills).

It’s important to note that the Betta smaragdina has been heavily hybridised with other fishes in the complex. They were initially crossbred for fighting purposes and now done so for aesthetics. 

You’ll commonly find “guitar”, “alien”, or “copper” variations of the Betta smaragdina with different colourations. I’m not well-versed with the above terminologies so if you have any information to share, please contribute!


You can try your hand at raising these fascinating types of species where they show beautiful colours and interesting behaviour. Raising them should not be an issue as it takes little effort and low levels of maintenance.

Have any information or images to share? Contact me and I’ll add them to this article!

2 Responses

    1. Hi there! I don’t think they can crossbreed due to them being different species, it’d be interesting if you shared any successes! 🙂

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