Looking for a colorful schooling fish for your freshwater community aquarium? Tetras and rasboras are the logical choices, but wait! Have you considered a rainbowfish? One of our favorites is the dainty, elegant Celebes rainbowfish, a blue and yellow gem from Indonesia. We'll tell you why it's so great, plus how to best care for it in your tank, in the guide below.
How dainty is this little rainbowfish? Between their slender body shape, metallic blue lateral (side) stripe and yellow and black accents, both male and female Celebes rainbows are real lookers. It's the boys that win out, though: their fins are extra long and fancy, and can be extended like tiny sails to woo the females.
Celebes rainbows grow to a maximum length of around 3". Note the upturned pectoral fins, which are typical for small rainbowfish and make them look like they're always cheering for something. Woohoo, rainbowfish!
This fish was known as Telmatherina ladigesi until 1998, when researchers found it was notably different from other Telmatherina species. As such, they gave it a genus of its own (of which it's still the only member): Marosatherina . This probably didn't come as a surprise to anyone, as it was always an odd duck in the overarching family Telmatherinidae. True Telmatherina live in lakes — particularly the iconic Malili Lakes, also home to Sulawesi shrimp — but the Celebes rainbowfish is only found in rivers. Marosatherina ladigesi it is.
Did you know? Depending on who you ask, Celebes rainbowfish and other Telmatherinidae (sailfin silversides) aren't true rainbowfish. Some consider them to be members of an overarching rainbowfish family (Melanotaeniidae), while others insist they're separate and therefore don't deserve the title. They'll always be rainbows to us, though 😉
As its name suggests, the Celebes rainbowfish is naturally found on the island of Sulawesi (formerly Celebes) in Indonesia. It exclusively inhabits a handful of rivers on the south side of the island, where it's known as "beseng-beseng". This region is characterized by its sheer, forested limestone karst cliffs and many waterways.
Indonesian sources provide a lot of information on what Celebes rainbowfish habitat actually looks like. That comes in handy for aquarists trying to make them comfortable in our tanks! According to different ecological overviews, these rainbowfish inhabit the upper river reaches (though presumably not true hillstreams), where the water flows clear and relatively quickly.
Local rainbowfish researchers, quoted in a 2020 article on this species, report the fish spending most of their time in deeper pools that feature slower water flow (lubuk), but using the rapids or riffles (parung) to forage. Aquatic plants aren't common in these river systems, but vegetation can be abundant around the edges. This provides cover for the rainbowfish, which seem to use the riverbanks as well as the lubuks to escape high-flow areas and for cover.
The substrate in Celebes rainbowfish habitat varies (sandy to gravelly to large rocks), while pH readings range from just above neutral to quite alkaline (7.3–8.8). Temperatures fluctuate between pretty chilly to seriously toasty: 68–90 °F. We've seen some websites mention that Celebes rainbowfish are also found in brackish estuaries, but none of the Indonesian sources confirm this — it might just be a myth!
Unfortunately, Celebes rainbowfish are threatened in their natural habitat. The IUCN Red List considers them Vulnerable due to their small natural range, overharvesting for the aquarium trade (including using poison), sand dredging in their native rivers, and pesticide runoff from surrounding rice paddies.
The 2007 paper mentions that these rainbowfish are now so rare most locals haven't heard of them, with ornamental fishermen stating they have to travel further and further to find the right species. Luckily these little rainbows are increasingly bred in captivity!
Celebes rainbowfish will do well in tanks of 20 gallons (long, for swimming space) or up. They're small but pretty active, so they don't make a good choice for a nano aquarium! The ideal Celebes rainbow system combines open space with plenty of plants and decor around the margins. You can keep the flow level low to moderate, though the rainbows won't mind higher-flow zones either.
Want to imitate the natural habitat of the Celebes rainbowfish as closely as possible? Cool! You don't see Sulawesi river biotopes very often. A sandy substrate interspersed with differently sized rounded river rocks and pebbles, maybe with the occasional leaf or branch, should look great.
You can imitate the marginal vegetation these fish like to hang out in by having riparian plants like reeds emerge from the sides of the tank, or try terrestrial plants with their roots hanging down in the water.
Although Celebes rainbowfish are considered an acceptable choice for the beginning aquarist, you'll need to keep a close eye on the water parameters. They're known to be sensitive to low water quality, so stay on top of weekly water changes. Never introduce any fish into an uncycled aquarium !
Rainbowfish are usually associated with very hard and alkaline water, but that isn't necessarily the case here. Real readings from their natural habitat show a pH as low as 7.0. Hardness measurements are almost impossible to find — the one reading we've come across actually mentions soft water — but in our experience, you can't miss if you aim somewhere in the middle.
Celebes rainbowfish do best in schools of at least 6–8 fish. They also get along swimmingly with many other peaceful community species. We've found that as long as the fish you're considering is too small to eat a rainbowfish, doesn't nip at long fins and thrives in similar water values, it'll most likely work.
Why not keep your Celebes rainbows with:
Want to go for that biotope instead? Your LFS might just carry some species that the Celebes rainbowfish, according to Indonesian fish surveys, live alongside in the wild:
Yes, Celebes rainbowfish are safe to keep with shrimp. True, we wouldn't keep them rainbows with our prized bee shrimp, but then again we wouldn't keep those with any fish! Quick breeders whose colony can absorb the occasional loss, like Neocaridina , should do fine in a well-planted Celebes rainbowfish tank. You can also go for the bigger Amano shrimp .
Still worried? A smaller rainbowfish like the spotted blue-eye may be a better choice for you.
Did you know? The Celebes rainbowfish probably comes across shrimp in its natural habitat. Its range overlaps with those of Caridina jeani and C. sulawesi . It may also live in the same waters as the green lace filter shrimp ( Atyoida pilipes ), which in any case likes similar habitats and would make a good tankmate!
Your Celebes rainbowfish starter pack:
A study of the stomach contents of wild Celebes rainbowfish reveals them to be micropredators. They mainly feed on small insect larvae, but also eat mollusks, zooplankton ( Daphnia , rotifers), and small amounts of phytoplankton. This generalist nature means keeping your pet Celebes rainbowfish well-fed is a breeze. They'll eat anything you feed the tank as long as the flakes or granules are small enough; you can try a carnivore or special insectivore formulation.
Don't forget to regularly mix things up with servings of frozen foods like bloodworms, or even live options like Daphnia . Seeing your fish employ their natural hunting instincts is pretty cool, and most live foods are more nutritious than formulated options.
Given their highly vulnerable status in the wild, captive breeding of Celebes rainbowfish is important. If you keep a group of these gorgeous rainbows in your (community) aquarium, why not try your hand at getting them to reproduce? They're typical mop-laying egg scatterers that can and do spawn in home tanks.
Like many tropical fish, wild Celebes rainbowfish breed at the start of the rainy season. If yours are in the mood, the males' behavior will give them away: they become increasingly territorial, flaring their fins and even biting any rivals that enter the area they consider theirs. No need to worry, though, as these are just sparring sessions. The loser retreats before anyone can get hurt.
You can check out our full breeding guide for egg-scattering fish if you'd like to know how to get your rainbows to reproduce. One thing particular to Celebes rainbowfish is that Daphnia water fleas seem to be the way to go when it comes to feeding both the parents (adult Daphnia ) and the babies (newborn Daphnia ). An Indonesian experiment found more eggs laid and a higher fry survival rate when the rainbows were fed water fleas compared to mosquito or midge larvae.
Celebes rainbowfish aren't at the top of the "small rainbowfish popularity checklist" — that honor probably goes to the threadfin rainbowfish , Iriatherina werneri . You may have to do some searching to find yours. Some aquarium stores can order fish in for you if you're willing to wait a few weeks, or you can consider shopping online instead.
We're proud to offer you our very own, vibrant and healthy Celebes rainbowfish at The Shrimp Farm. Get your fish shipped straight to your doorstep with our live arrival guarantee!
Hadiaty, R. K. (2007). Kajian Ilmiah Ikan Pelangi {Marosatherina ladigesi (Ahl 1936)} Fauna Endemik Sulawesi. Berita Biologi , 8 (6), 473-479.
Iqram, M., Litaay, M., Hasyim, Z., Moka, W. J. C., & Tinungki, G. M. (2024). Combining eDNA metabarcoding and conventional method in rapid screening of fish diversity in Maros-Pangkep Global Geopark, South Sulawesi, Indonesia. Biodiversitas , 25 (2), 819-828.
Jayadi, J., & Husma, A. (2016). Domestication of celebes rainbow fish (Marosatherina ladigesi). Aquaculture, Aquarium, Conservation & Legislation , 9 (5), 1067-1077.
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Pratiwi, Y., & Fahri, A. Udang Air Tawar Genus Atyoida Di Sungai Pondo, Palu, Sulawesi Tengah, Indonesia The Freshwater Shrimp Of Genus Atyoida In Pondo River, Palu, Central Sulawesi, Indonesia. Online Journal of Natural Science Vol , 5 (2), 192-198.
von Rintelen, K., Rumpf, C. M., Wowor, D., Wessel, A., & von Rintelen, T. (2024). A phylogeographic approach to Sulawesi’s Maros karst shrimp fauna (Decapoda, Atyidae) reveals several cave invasions and challenges current taxonomic hypotheses. Crustaceana , 97 (5-9), 479-505.