Why Do Sulawesi Shrimp Need Warm Water?

You’ve put a heater on the Sulawesi tank, the care sheet says 79-86°F (26-30°C), and you’d like to know whether that number is real. It is: Sulawesi shrimp need warm water because they’re endemic to the ancient lakes of central Sulawesi,¹ and that water stays warm, with Lake Towuti reported at about 82°F (28°C) all year.² In your tank that becomes 79-86°F (26-30°C), and holding one figure inside that band matters more than which end of it you pick.

Each lake has its own species, so the trade name covers several lakes. The Sulawesi White Sock cardinal shrimp, Caridina dennerli, is restricted to Lake Matano and Caridina glaubrechti to Lake Towuti.¹

Where the Sulawesi temperature range comes from

It’s copied from two lakes that have been measured, not from a number the hobby settled on by agreement. Those measurements are worth a direct look, because they say something the usual care sheet doesn’t.

Read the table again and the striking figure isn’t the heat. It’s how little anything moves. The air over the catchment barely changes between months, and the water under it barely changes at all. These shrimp aren’t adapted to a hot tank so much as to a tank that doesn’t argue with itself.

That’s the part most keepers get wrong. They buy a heater and then let the room decide the rest. So what does your tank do between a warm afternoon and dawn? If it drifts several degrees, it’s doing something the reported lake figures don’t describe, and it’s doing it every day.

How much to trust the lower temperature limit on a Sulawesi care sheet

Not much, because none of those floors traces back to a measurement. Every care sheet gives one. Some say the shrimp stop feeding below a certain figure, others give a temperature at which molting fails or a colony collapses. The pages that rank for this question don’t cite a measurement for any of it, and their figures don’t agree with each other. We haven’t found a published lower lethal limit or critical thermal minimum for any Sulawesi lake Caridina.

The closest thing to measured data is a 2025 rearing trial on Caridina dennerli. It grew shrimp of about 1.4 cm total length under four feed and shelter treatments, and it recorded its tank water at 79.5°F to 83.7°F (26.4°C to 28.7°C).⁴ That trial was testing food and shelter, not temperature, so it tells you nothing about a floor. What it does tell you is simpler. The one piece of controlled work on one of these species was done inside the same band the care sheets recommend. That’s a better reason to stay there than any cutoff being quoted at you.

The lakes don’t hand you a floor either. In Lake Towuti, the upper 90 m of water runs cooler, with more mixing, in the July to September dry season.⁵ That’s a slow seasonal shift in a deep lake, not a daily swing in a glass box. There’s no tolerance test behind it, so it doesn’t license running your tank cool.

Warm water holds less oxygen, so a Sulawesi tank needs gentle surface movement

Cold water can hold more dissolved oxygen than warm water, so a warm Sulawesi tank starts with a smaller oxygen reserve.⁶ That’s the first thing the Sulawesi range costs you. Near the top of the band, your tank has less dissolved oxygen to spare than it would at room temperature. That spare is what covers you when something goes wrong overnight.

Does that mean you need a stronger pump? No. These are lake animals that graze the biofilm on rock and hardscape, and what your tank needs is gas exchange. That comes from surface area and a surface that keeps moving, not from current racing along the substrate.

Why the same ammonia reading is more dangerous in a warm Sulawesi tank

Because Sulawesi water is warm and alkaline at the same time, and both push more of the ammonia into its toxic form. The water has to sit at pH 7.5-8.5, so this is where temperature stops being only a heating question.

Total ammonia in fresh water sits in equilibrium between the ammonium ion and un-ionized ammonia, and it’s the un-ionized form that drives toxicity. High external un-ionized ammonia reduces or reverses the diffusive gradient an animal uses to get rid of it, so ammonia builds up in its tissues and blood. That share isn’t fixed. It rises about tenfold for each single pH unit, and roughly doubles for each rise of 10°C (18°F) between freezing and the top of the Sulawesi band.⁷

None of that’s specific to these shrimp. What’s specific is that the water they need puts them at a high pH and a high temperature at once. So the same total ammonia reading doesn’t mean here what it would mean in a soft acidic Bee tank. That’s a fair part of why this group has a reputation for being unforgiving. The animals aren’t fragile in some mysterious way. The chemistry they need turns small Sulawesi shrimp care mistakes into larger ones.

Whether running a Sulawesi tank hotter or cooler is a lever worth pulling

No, neither end of the range buys you what it sounds like it should, and the lever that works is steadiness. Two shortcuts tempt most keepers here. Can you sit at the top of the range to push growth or breeding along, and can you sit at the bottom to play it safe?

Running hot can mean more molts without more growth. In lesser blue crabs, animals reared at elevated temperature molted at shorter intervals but grew less each time.⁸ More frequent molting isn’t the same thing as faster growth, and a shrimp isn’t owed extra size for the extra heat.

Running cool has its own cost. In a wild river Caridina from Japan, growth was generally low while the water was cooling and picked up again as it warmed.⁹ Cooler water buys you nothing the shrimp want.

So choose one Sulawesi shrimp temperature inside 79-86°F (26-30°C) and hold it through the coldest and warmest hours of your day. If your room can’t hold that number on its own through a cold night, your Sulawesi shrimp need a heater with an independent controller.

Sort the heating and the surface movement first, then decide which tank-bred Sulawesi shrimp you want to start with. A tank that already holds one temperature without supervision is most of the difficulty of this group solved before the animals arrive.

What the research says about warm water for Sulawesi shrimp

The evidence on running a tank warmer or cooler comes from other crustaceans. Temperature has been shown to affect both the interval between molts and how much an animal gains at each molt in many crustaceans. Lesser blue crabs reared at elevated temperature molted at shorter intervals but grew less each time, and ended up smaller at every instar. The authors note that if the pattern held through the pubertal molt, warmer animals would also be smaller at maturity.⁸ That’s a crab, not a lake shrimp, so take the direction and leave the details.

The evidence on cool water comes from a closer relative. In a wild population of the amphidromous shrimp Caridina leucosticta in a Japanese river, growth was generally low while the water was cooling.⁹ It picked up again as the temperature rose. That’s a temperate river species, not a Sulawesi lake species, so read it as a direction and not as a figure for your tank. The direction is the useful part: it gives you no reason to run a Sulawesi tank cool.

References

9 Sources

1. Radiation of endemic species flocks in ancient lakes: systematic revision of the freshwater shrimp Caridina H. Milne Edwards, 1837 from the ancient lakes of Sulawesi, Indonesia, with the description of eight new species, von Rintelen and Cai, The Raffles Bulletin of Zoology 57(2), 343 to 452, 2009.
2. Geomicrobiological Features of Ferruginous Sediments from Lake Towuti, Indonesia, Vuillemin and others, Frontiers in Microbiology 7, article 1007, 2016.
3. The biogeochemistry of tropical lakes: A case study from Lake Matano, Indonesia, Crowe and others, Limnology and Oceanography 53(1), 2008, repository record and abstract.
4. Effect of Using Different Shelter and Feed Types on Growth and Survival Rate of Sulawesi Endemic Ornamental Shrimps (Caridina dennerli), Abdullah, Hasim and Mulis, Jurnal Ilmiah PLATAX 13(1), 191 to 204, 2025, journal PDF.
5. Hydrological connectivity and mixing of Lake Towuti, Indonesia in response to paleoclimatic changes over the last 60,000 years, Costa, Russell, Vogel and Bijaksana, Palaeogeography, Palaeoclimatology, Palaeoecology 417, 467 to 475, 2015, hosted copy.
6. Dissolved Oxygen and Water, U.S. Geological Survey Water Science School, updated August 24, 2026.
7. Aquatic Life Ambient Water Quality Criteria for Ammonia, Freshwater, U.S. Environmental Protection Agency, Office of Water, April 2013.
8. Elevated temperature induces a decrease in intermolt period and growth per molt in the lesser blue crab Callinectes similis Williams, 1966, Kuhn and Darnell, Journal of Crustacean Biology 39(1), 22 to 27, 2019, abstract.
9. Life history of the amphidromous shrimp Caridina leucosticta in the Isazu River, Japan, Yatsuya, Ueno and Yamashita, Journal of Crustacean Biology 33(4), 488 to 502, 2013, abstract.