Celebes Rainbowfish
Marosatherina ladigesi
Min Tank Size
60L
Adult Size
7 cm
Lifespan
4 years
School Size
6+
About
Native to the Maros river system in Sulawesi, Indonesia, Marosatherina ladigesi is one of the most visually striking fish you can keep in a smaller community setup. The body is semi-translucent with a faint blue-green iridescence, and the fins are where it really shows off. Males develop elongated rays on the dorsal and anal fins, edged in black with vivid yellow, giving them an almost ornate, feathered look. Females are plainer but still attractive. At around 7 cm fully grown, these are not tiny fish, but they're slender enough to feel right at home in a 60-liter tank when kept as a group.
Water chemistry is where most people go wrong with this species. They come from hard, alkaline water and genuinely need it. 0 will stress them quickly, and soft water leads to faded color, lethargy, and shortened lifespan. If your tap water is soft, regular mineral supplementation or crushed coral in the filter is worth considering.
Diet-wise they're not fussy. They'll take quality flake, micro pellets, and really shine when given regular offerings of small live or frozen foods like daphnia, cyclops, or baby brine shrimp. Color pops noticeably with a varied diet.
Keep them in groups of at least six to see natural schooling and male display behavior. A single specimen or a pair rarely thrives socially. They're peaceful, active swimmers that make a stunning centerpiece in a well-planted, slightly alkaline community tank.
Water Parameters
Temperature
°CpH
GH
dGHKH
dKHSwimming Level
Flow Preference
Keeping multiple Celebes Rainbowfish together
Celebes Rainbowfish are shoaling fish and need company of their own kind. Keep a group of at least 6. Smaller groups leave them stressed, washed-out in color, and prone to hiding.
Compatibility
These fish do best with calm, similarly sized tankmates that won't stress or harass them. Good choices include other peaceful community fish from harder water environments, like certain livebearers (platies, mollies), smaller rainbowfish species, and peaceful gobies. Avoid any confirmed fin nippers like tiger barbs or serpae tetras since the male's long fin extensions are a magnet for nipping. Large or boisterous species are also a bad match. Dwarf shrimp are a gray area since Celebes rainbowfish may pick off newly molted shrimp or very small juveniles, though adult shrimp are typically left alone. Snails coexist without issue.
Commonly kept with
Species this one is most often paired withCommonly tried but avoid
Often paired, but shouldn't beCare Notes
The biggest beginner mistake is keeping these in soft or acidic water. They will survive short-term but color fades, behavior dulls, and you'll see unexplained deaths within months. Hard water with a pH of 7.5 or above is genuinely required, not optional. Water quality sensitivity is high, so weekly partial changes of around 25-30% are necessary. They're not great candidates for heavily planted tanks dosed with CO2, since CO2 injection drops pH and KH over time. Feeding small, varied foods two to three times daily keeps them in peak condition and brings out the best color in males.
Behavior & Aggression
Celebes rainbowfish are genuinely peaceful toward other species. The only real intraspecific tension happens between rival males, who will flare and display at each other, especially during feeding or when one male chases another away from a preferred spot. This is mostly harmless posturing and actually looks spectacular in a well-lit tank. Occasional brief chasing occurs but rarely escalates to fin damage if the group is large enough and the tank has some visual breaks via plants or decor. No meaningful aggression toward other species has been documented.
Things to Know
- Can jump. A tight-fitting lid is essential.
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