Why Sulawesi Shrimp Die After Introduction

Did your new Sulawesi shrimp start dying within days of going into the tank? The cause is almost never something you can treat: it’s nearly always the water they moved into, or a tank that had finished cycling but hadn’t finished maturing. That’s why the useful work now is measuring, waiting and leaving the tank alone, not dosing it.

What to do in the first hour after finding dead Sulawesi shrimp

Take the dead shrimp out, then gather information before you change anything. Almost every instinct at this moment makes the tank less stable, and instability is what’s killing the shrimp. A big water change, a dose of minerals, a medication or a few extra degrees on the heater all move the water further. Every one of those moves lands on animals that are already struggling.

• Remove the dead shrimp so they don’t add to the waste load, and look at each one before you discard it.
• Test ammonia and nitrite first. Both should read zero in a tank that’s ready to hold livestock.
• Read the temperature at the glass, not off the heater dial.
• Test pH, GH, KH and TDS, and write the numbers down so the next reading means something.
• Write down everything you changed in the past two weeks, including top offs, new rock, a new mineral batch and any food you started using.
• Don’t run a large water change to try to fix a reading you haven’t identified yet.
• Don’t add medication. Copper and some fish medications can harm shrimp and snails, and nothing here has been identified as a disease.

If the shrimp arrived recently, keep the rest of the box out of it. Don’t move survivors to a second tank in the middle of a die off unless that tank already runs at the same chemistry and temperature, because the move itself is another transfer.

How long after introduction they died narrows the cause

When it happened is the most useful clue you have. Problems at the transfer and problems already waiting in the tank don’t fail on the same schedule, so sorting the two apart tells you where to look. The table below lists plausible categories to check, in the order Sulawesi tanks usually fail.

None of these rows is a diagnosis, and none of them can be confirmed from appearance alone. They tell you where to spend the next hour. A tank can also be running two of them at once.

Compare your tank against the Sulawesi range, then against itself

Start with the group range, because a tank outside it won’t recover on patience alone.

Then do the harder comparison: your tank against itself. Take a reading, take another a few days later, and look at the difference instead of the value. Is the tank sitting quietly inside the range, or reaching the same numbers by drifting up and being corrected back down? A single test makes those two tanks look identical, and they aren’t.

Steadiness is the part of the water this group is least willing to negotiate on. Lake Towuti, one of the Malili lakes these shrimp come from, has a tropical humid climate with little variation in monthly temperatures. Its surface water sits in a narrow warm band with only weak thermal stratification through the column.² Nothing in that Sulawesi natural environment prepares an animal for water that moves.

Two mundane sources account for most of that movement. The first is topping up. Evaporation concentrates dissolved solids in the water left behind, a mechanism USGS describes for shallow groundwater in arid regions,³ and the same physics applies to an open aquarium. A tank topped up with remineralized water gains minerals it never lost, so top off with pure water only. The second is replacement water that was mixed in a hurry. It arrives at a different chemistry from the tank it’s entering, and a routine water change turns into the shock you were trying to avoid.

Check the substrate and hardscape for something that’s spending your buffer

The usual thing spending your buffer is an active substrate, though peat and botanicals can do it too. Alkalinity is the water’s capacity to neutralize acids and hold a fairly stable pH, and it comes from bicarbonates, carbonates and hydroxides in the water. Water with high alkalinity changes less when acid enters it than water with low alkalinity does.⁴ In a Sulawesi tank, that carbonate buffer is what holds the water at the alkaline pH the shrimp expect. Anything quietly consuming it is a slow leak under everything else you do.

Soils sold for Bee and Crystal Caridina are built to bind minerals out of the water and hold pH down, which is exactly right for those shrimp and exactly wrong here. Set a Sulawesi tank up on aquasoil and it’ll keep losing buffer no matter how carefully you prepare the replacement water. Keep peat, botanicals and anything else sold to soften or acidify water out of this tank too. The best substrate for Sulawesi shrimp is inert, like the hardscape, and the buffer comes from the prepared water instead.

If your tank is on an active soil, no amount of dosing will hold the line. That’s a Sulawesi shrimp tank reset, and it’s better done with the surviving shrimp moved to matched water than attempted underneath them.

Sulawesi mineral water that wasn’t finished before it went in

Sulawesi Mineral 8.5 water causes trouble when it goes in before it has fully dissolved and been aerated. It catches careful keepers, because the mistake happens in a bucket, not in the tank. The manufacturer states that it will almost totally dissolve if CO2 is added for a few days. At a regular CO2 quantity of one bubble per second, the salt dissolves totally in approximately 3-4 days, and the water must then be aerated with an air stone for at least three hours to expel the CO2 before use. It raises carbonate and total hardness at a ratio of KH to dH of 0.78 to 1.0.⁵

Two things go wrong with that sequence. Water that never fully dissolved goes in cloudy, carries undissolved mineral and doesn’t lift pH the way the label says it will. Water that dissolved but wasn’t aerated for the stated minimum goes in still carrying the CO2 you were told to expel. Once carbon dioxide dissolves in water, it reacts with water molecules to form carbonic acid, and the lower the pH value, the higher the acidity of a liquid.⁶ That’s why a batch still holding CO2 reads lower in the bucket than it will settle at, and why the reading you took an hour ago isn’t the water the shrimp are in now. Either way the animals get a moving target. If the batch went in on the day the shrimp arrived, the two events are hard to tell apart.

What changes if you prepare water with Sulawesi Mineral 7.5

The 7.5 formulation takes the bucket problem away. The manufacturer states that it will almost totally dissolve within seconds and the water is ready for use immediately, with no CO2 step. It buffers the pH at around 7.5 and raises carbonate and total hardness at a ratio of KH to dH of 0.42 to 1.0.⁷ That’s a real advantage when you’re trying to rule out variables during a die off. It also parks the tank at the bottom of the group pH range, so there’s less room above you if something starts pulling pH down. Whichever you use, the value that counts is the one you measure in the finished water.

Why feeding a new colony is the riskiest thing you can do this week

Feeding is risky because a warm, alkaline tank turns the same ammonia reading into a worse one, and extra food gives the system more to break down. New shrimp that aren’t eating look like they’re starving, and the natural response is to feed more. In a warm alkaline tank, that response is how a survivable week becomes a fatal one.

Total ammonia in water sits in equilibrium between the ammonium ion and un-ionized ammonia, and it’s the un-ionized form that drives toxicity. In fresh water, the ratio of un-ionized ammonia to ammonium ion increases 10-fold for each rise of a single pH unit. It roughly doubles for each 10 degrees Celsius rise in temperature from 0 to 30 degrees Celsius.⁸ A Sulawesi tank is warm and alkaline by design, so the same number on the same test kit means more trouble here than in a cool, soft water tank.

The oxygen side works against you at the same time. Cold water can hold more dissolved oxygen than warm water,⁹ so a warm Sulawesi tank has less oxygen in reserve just when you’ve given the system something extra to break down. Aeration and surface movement matter more here than they do in a cool tank.

The practical answer is unglamorous. Add no prepared food for the first days, let the shrimp graze the rock, and take out anything they haven’t eaten before it breaks down. If the rock has nothing on it to graze, that’s the real finding, and food isn’t the fix for it.

A shrimp that died mid molt is telling you about the water

A shrimp that died part way out of its old shell points at the mineral content of the water, not at food or disease. You’ll see a visible gap across the back between the carapace and the abdomen, and it’s a common sight after a rough introduction. Keepers call it the white ring of death, which describes what you’re looking at, not what happened.

It points at chemistry because of where the shell material comes from: in crustaceans, most of the calcium for a new exoskeleton comes from the water the animal lives in, not from its food.¹⁰ In your tank, that means the mineral content of the water and its steadiness are what a molting shrimp draws on. A supplement added at the moment of a die off is neither fast enough nor stable enough to help.

So read the GH and KH, read them again in a few days, and check whether either has moved since the shrimp went in. Correct the water slowly toward the range and then hold it there. Don’t dose the tank in the middle of a die off. If losses continue while your parameters sit inside the range and stay put, that’s the point to bring in a qualified aquatic veterinarian or an experienced local specialist. Losses that continue after the water settles are a different pattern, Sulawesi shrimp dying gradually.

What the research says about Sulawesi shrimp dying after introduction

Two of the mechanisms behind this guide come from work on other aquatic animals, not on Sulawesi shrimp. Read them as the reason behind the advice, not as a figure for your tank.

The ammonia numbers come from US federal water quality criteria for freshwater aquatic life. The same criteria explain why the un-ionized form matters: high external concentrations of it reduce or reverse diffusive gradients and cause ammonia to build up in internal tissues and blood.⁸ The molting point comes from a review of biomineralization in crustaceans. It describes the major source of calcium for exoskeleton calcification as exogenous, meaning the surrounding water, while food, sometimes including the shed shell itself, is a minor contribution.¹⁰ Both point the same way as the advice above: steady, finished water and no extra food in the first days.

When a Sulawesi tank is ready to hold shrimp again

A Sulawesi tank is ready again when it’s mature, and cycled alone isn’t enough. Cycling means the filter processes waste. Maturity means there’s something on the rock to eat, and the chemistry has proven it will sit still for weeks without you steering it.

Use that as a floor, and let the tank tell you the rest.

• Ammonia and nitrite read zero on two tests several days apart.
• Temperature, pH, GH, KH and TDS have been logged for at least two weeks and aren’t drifting.
• Rock surfaces carry visible brown or green growth, so there’s something to graze on the day the shrimp arrive.
• Every batch of replacement water is prepared, finished and measured before it goes near the tank.
• Top off water is pure water only, so TDS doesn’t climb between water changes.
• Don’t restock because the calendar says the tank is old enough while a reading is still moving.

When the next order of Sulawesi shrimp does arrive, follow the acclimation instructions supplied with that shipment, not a general method from another site, because packing method, transit time and species all change the right answer. Whatever method you use, keep transport water out of the aquarium.

References

10 Sources

1. Effect of Using Different Shelter and Feed Types on Growth and Survival Rate of Sulawesi Endemic Ornamental Shrimps (Caridina dennerli), journal PDF, Jurnal Ilmiah PLATAX 13(1): 191-204, 2025.
2. Geomicrobiological Features of Ferruginous Sediments from Lake Towuti, Indonesia, Frontiers in Microbiology 7, article 1007, 2016.
3. Chloride, Salinity, and Dissolved Solids, U.S. Geological Survey, Water Resources Mission Area, March 1, 2019.
4. Alkalinity and Water, U.S. Geological Survey Water Science School, updated August 24, 2026.
5. SALTYSHRIMP, Sulawesi Mineral 8,5, manufacturer product information page, SaltyShrimp (Garnelenhaus), no revision date shown.
6. Understanding the Science of Ocean and Coastal Acidification, U.S. Environmental Protection Agency, updated August 24, 2026.
7. SALTYSHRIMP, Sulawesi Mineral 7,5, manufacturer product information page, SaltyShrimp (Garnelenhaus), no revision date shown.
8. Aquatic Life Ambient Water Quality Criteria for Ammonia, Freshwater (2013), U.S. Environmental Protection Agency, Office of Water, April 2013.
9. Dissolved Oxygen and Water, U.S. Geological Survey Water Science School, updated August 24, 2026.
10. Biomineralizations: insights and prospects from crustaceans, ZooKeys 176: 103-121, 2012.