Sulawesi shrimp and Tylomelania snails: warm alkaline water, stability and conservation

Why Sulawesi species are different

Sulawesi Caridina shrimp (cardinal, harlequin, yellow cheek, blue leg Poso and others) and Tylomelania snails come from the Indonesian island of Sulawesi, mostly from its ancient lakes – the Malili lake system (Matano, Mahalona, Towuti) and Lake Poso. Many species live in a single lake and nowhere else.

The water there is warm all year and mildly alkaline – the opposite of what crystal and bee shrimp need. The active soil and acidic water those shrimp rely on, and the CO₂ of planted tanks, would harm Sulawesi species.

They are sensitive to ammonia, nitrite, copper, medications and swings in water chemistry, and they are not a first shrimp. Take them on once you have kept other shrimp and can hold your water steady.

Water: what is known and what isn’t

Field data are thin and the sources contradict each other. The Malili lakes are reported at roughly 81–88 °F (27–31 °C). For Lake Matano, the scientific revision of Sulawesi shrimp gives a pH of about 7.4, while Indonesian surface measurements from 2008–2016 put it at roughly 8.2–8.9. For other lakes, Poso included, the data are scattered and inconsistent.

Aquarium practice departs from the field data, and keepers don’t agree either. Rough ranges used in aquariums:

• temperature 81–86 °F (27–30 °C),
• pH about 7.5–8.5,
• GH about 4–8 °dGH and KH 3–6 °dKH,
• TDS – recommendations vary more than for other shrimp, roughly 100 to 300 ppm, and lower by some accounts; use it mainly to check that your water stays the same,
• ammonia and nitrite at zero, nitrate as low as you can keep it.

Sulawesi mineral salts come in several versions, each rated by the maker for a different pH, for example around 7.5 or 8.5; the pH you actually get in the tank can differ. Which one to use depends on the species and the water the animals have been living in; ask the breeder you get them from and start with water close to theirs.

In SUISO, “Suggest from livestock” in the tank’s targets fills in a rough shared range for pH, KH, GH and TDS from the catalog for the species you keep. For Sulawesi species, treat it only as a starting point: adjust it to the water your animals are thriving in, and log TDS under “More values” when you enter a water test.

Stability over exact numbers

Swings in water chemistry are among the most common reasons Sulawesi shrimp die. A larger tank helps because its water changes more slowly, and so do small, regular water changes instead of big ones – keepers suggest no more than about 10 % at a time.

Mix new water ahead of time from RO water and Sulawesi salt, check its TDS and pH and bring it to tank temperature. Add it slowly.

Top off evaporation with plain RO water, no salt. Minerals don’t evaporate, so topping off with salted water keeps pushing TDS up, and skipping top-offs concentrates the water.

Leave out CO₂, active soil, peat and fertilizer-rich substrates. Keep planting light, because photosynthesis swings pH over the day. Inert sand or fine gravel and rocks that grow biofilm work well.

When something is out of range, bring it back slowly, over several days. With these shrimp a quick fix is a bigger risk than a value that is slightly off.

Tank maturity, biofilm and feeding

Don’t put Sulawesi shrimp into a new tank. Zero ammonia and nitrite aren’t enough: the shrimp live mainly on biofilm on rocks, and that takes time to grow. Sources most often recommend letting the tank mature for two to four months.

Feed sparingly with fine foods – only what the shrimp clear within an hour or two – and remove leftovers. In warm alkaline water more of the ammonia is in its toxic form, so rotting food does harm faster.

Tylomelania snails are big eaters and need more food than typical aquarium snails, but their leftovers load the water for the shrimp too. Keep just one or a few snails in a shrimp tank. They give birth to one young at a time, so numbers grow slowly.

One shrimp species per tank

Keep only one Sulawesi shrimp species per tank. Some keepers report that species interbreed in aquariums, while other sources say they don’t; either way, hybrids would be worthless for keeping the species going. The species also come from different lakes and their needs differ. Keep Tylomelania species apart as well: they hybridize in the wild and are hard to identify in the trade.

Tylomelania snails can share a tank with Sulawesi shrimp; they need similar water.

Neocaridina won’t interbreed with Sulawesi shrimp, but they need cooler, different water, so they don’t belong together; the same goes for crystal and bee shrimp. Fish are a poor fit: the shrimp are tiny and their young wouldn’t survive.

Conservation: captive-bred, never released, not an experiment

Many Sulawesi shrimp and snail species are listed as Critically Endangered on the Red List of threatened species. Threats include nickel mining, pollution and introduced species: flowerhorn, an artificially bred cichlid hybrid, turned up in Lake Matano around 2010, most likely released from an aquarium, and has since spread to neighboring lakes. For some species, collection for the aquarium trade is also listed among the threats.

• choose captive-bred animals over wild-caught ones – for some species much of the trade still comes from the wild, so ask the seller where the animals came from,
• never release animals, plants or aquarium water into the wild,
• don’t keep them as an experiment – they are demanding and die in unsuitable conditions; buy them once you have a mature tank, steady water and a plan for the offspring,
• keep the offspring, or pass them on to a keeper who maintains the same species on its own.

What to log

Temperature and TDS every few days, pH, GH and KH now and then, water changes with the volume, the salt and the TDS of the new water, and every top-off. For Sulawesi species the general ranges are uncertain, and your own numbers from the time your animals were thriving are the best guide. Note the species, where the animals came from (captive-bred or wild-caught) and how many you have. Log deaths as livestock losses with their cause, and berried females and young as a good sign; when you ask the Advisor, it sees them in your journal next to the water changes and tests from the days before.