Caridina shrimp, including Crystal Red, Crystal Black, Golden Bee, Pure Red Line and Taiwan Bees like Blue Bolt, King Kong and Pinto, are the jewels of the shrimp hobby. They need soft, slightly acidic water that stays the same from week to week. Most problems with Caridina come from unstable water, not from the shrimp themselves. This guide covers the setup and routine we have used since 2013, plus the fixes we've given customers over the years when their tanks ran into trouble.
Water parameters
| Parameter | Range |
|---|---|
| Temperature | 68–78°F (76–78°F is best for breeding) |
| pH | under 6.8 (as low as 5.5 in a new tank) |
| GH | 4–6 |
| KH | 0–1 |
| TDS | 100–120 ppm |
| Ammonia / nitrite | 0 |
| Nitrate | under 25 ppm (5–20 is ideal) |
We keep our Caridina at TDS 100–120, because we find they breed better at a lower TDS. New active soil pulls the pH down to around 5.5 at first; that's fine, and it settles over time. Pick a target inside these ranges and hold it there. A TDS that stays at 110 is much better than one that drifts from 100 to 150 and back.
GH matters more than TDS. A TDS meter tells you how much is dissolved in the water, not whether it's the calcium and magnesium shrimp need to molt. A tank can read a "good" TDS and still have GH that is too low. Test GH directly with a liquid test kit, and if you have to choose, get GH right first.
The water: RO/DI and remineralizer
RO/DI water is a must for Caridina. Tap water is too hard in most places, and its hardness changes during the year. We use 100% RO/DI water in every tank, even for cycling:
- RO/DI water: water from a reverse osmosis/deionization unit starts at a TDS near 0. Replace the unit's filter cartridges every 6–12 months, depending on use.
- A GH-only remineralizer made for Caridina: it adds calcium and magnesium without raising KH. Mix it into the RO/DI water until the TDS meter reads your target (for example 110 ppm), then check GH.
- Test kits: a TDS meter, plus liquid test kits for GH, pH, ammonia and nitrate. Cheap pH pens drift and give confusing readings; a liquid pH test is more reliable.
Mix new water a day ahead so it reaches room temperature and the minerals fully dissolve. Remineralize the water before it goes into the tank, so the shrimp never see a sudden drop in GH and TDS.
Tank setup
- Size: 10 gallons minimum. 20 gallons is the sweet spot: large enough to stay stable, small enough to keep an eye on the shrimp.
- Active soil: a must. It buffers the water to a low pH and keeps KH at 0, which plain gravel can't do. We have bred Caridina on ADA Amazonia for years with no issues. Even a thin layer is better than a bare bottom: it gives shrimp something to grip and graze, and room for beneficial bacteria to grow.
- Filter: use at least a sponge filter. Sponge filters are low maintenance, safe for babies and give the gentle flow shrimp prefer. Shrimp don't like strong current, so a powerful filter does more harm than good.
- Frogbit: we keep frogbit floating in every tank. It grows fast and soaks up excess nitrate, so the tank needs far fewer water changes.
- Moss: moss gives shrimp places to hide and graze. It's also the easiest plant for a shrimp tank: it needs no fertilizer, no CO2 and no extra care, unlike high-maintenance plants. Rinse new plants and moss well and check them for pests like hydra before they go in.
- Driftwood: safe for shrimp, but new wood releases tannins that raise TDS and lower GH and pH for a while. Watch GH closely if you add wood.
- Temperature control: a heater if your room gets cold, and a fan or chiller if it gets warm. Breeding is best at 76–78°F. Above about 84°F Caridina get stressed and become inactive, so plan for summer.
- One tank, one system: we keep each tank on its own rather than linking several tanks to shared water. Linked tanks are easier to keep even, but one bacterial infection spreads to all of them.
Cycling a new tank
Most Caridina losses in new tanks come from adding shrimp too soon. This is how we cycle:
- Add the soil, plants and RO/DI water, then a beneficial bacteria product made for shrimp tanks. Hold off on minerals until the cycle is done.
- Keep the tank around 75–77°F. Cycling is slow below about 70°F.
- Don't do water changes during the cycle. Just top off evaporation with RO/DI water.
- New active soil like ADA Amazonia releases a big ammonia spike at first. With a strong bacteria product the tank cycles in 30–45 days, but we always wait the full 8 weeks so the tank matures and grows biofilm. Ammonia can come back after reading 0 early on, which is another reason to wait. A sponge from an established tank speeds things up, but still cycle for at least 30 days.
- Start testing ammonia after week 3, then once a week. The cycle is done when ammonia (and nitrite) read 0 and nitrate spikes above 40 ppm.
- Do a 100% water change with remineralized RO/DI water and let the tank run for a day.
- Start with a small group of shrimp and build up the population over the next months. A brand-new tank can't support 100 shrimp at once; it will crash.
Adding new shrimp
Caridina are sensitive to sudden changes, so take your time.
- Float the closed bag in the tank for 15–20 minutes to match the temperature.
- Pour the shrimp and their water into a clean container. Drip tank water in very slowly (1–2 drops per second) for 1–2 hours, until the water volume has roughly tripled. No drip kit? Add 1/4 cup of tank water every 15 minutes, four times.
- Net the shrimp into the tank. Don't pour the shipping water in.
- Keep the lights low for the rest of the day and wait a day before feeding.
New shrimp often hide for several days. Some may molt soon after arriving; leave the old shells in the tank so the shrimp can eat them. A few losses in the first week or two can happen as shrimp adjust, especially in a younger tank. Don't do water changes in a panic; wait it out and watch.
Feeding
Shrimp get about 70% of their food from biofilm in the tank; what you feed is a supplement, not their main diet. We feed 2–3 times a week, mainly snowflake food (soybean hulls), and once a week a fine baby shrimp powder such as Bacter AE for the shrimplets. Leftover snowflake doesn't foul the water the way pellets do, and overfeeding is one of the main causes of shrimp deaths.
- The 80% rule: when you add food, at least 80% of the shrimp should go for it. If they don't, they aren't hungry: skip the next feeding.
- Keep the menu short: one or two main foods plus a baby powder. With a dozen different foods, you'll never know which one caused a problem.
- Watch for deaths after feeding: shrimp that die the day after a feeding point to too much food or the wrong food. We stopped feeding protein foods for this reason.
Water changes and maintenance
For Caridina, the most important thing is a stable environment, and every water change is a chance for the water to shift. Our routine:
- Top off with plain RO/DI water, not remineralized water. Only water evaporates; the minerals stay behind, so topping off with remineralized water slowly pushes TDS up.
- Change water only when nitrate is high: do a water change when it goes above 25 ppm. Frogbit keeps it low in most tanks.
- When you do change water: use remineralized RO/DI water matched to the tank in TDS and temperature, and dose beneficial bacteria afterwards.
- If shrimp are active and eating, leave the tank alone. Changing things in a healthy tank is asking for trouble.
- Sponge filters: we only clean ours when they clog. When you do, rinse in removed tank water, never under the tap.
- Nets and tools: use a separate net for each tank and hang it to dry after use. Clean shared tools like tweezers and scrapers between tanks.
- Copper builds up: with few water changes, even a trace of copper in food or plant fertilizer accumulates over time. Check labels, and skip fertilizers in shrimp tanks.
- Testing: once a tank is stable and the shrimp are actively picking and eating, regular testing is optional; we rarely test ours. If shrimp turn sluggish, stop moving around or stop eating, check all the parameters right away.
Breeding
Caridina breed well once the tank is mature and the water is stable, and best at 76–78°F. Females are larger, with a deeper, rounder tail section. They carry eggs under the tail for about 30 days. The babies hatch fully formed but very small, and for the first weeks they live almost entirely on biofilm, which is why an established tank matters so much. The weekly baby powder food helps more of them grow up. Caridina reach breeding age at about 4–5 months and live around 1.5–2 years.
- Not too many males: when a female molts, every male chases her. In a crowded tank with too many males, the stress can kill her. In a breeding tank, keep fewer than about 10 adult males, and give the shrimp plenty of moss to hide in.
- Stocking: a rough maximum is 10 shrimp per gallon, but it depends on how strong the tank is. A weak tank can't hold that many; a well-established one can hold hundreds.
- Breeding pauses are normal: there are months, often in winter, when shrimp stop breeding. If they are active and healthy, don't change anything. It passes.
Our Caridina ship as unsexed juveniles about 1/4"–1/2" long. Start with 10 or more so you end up with both males and females.
Mixing Caridina
Crystal Red, Crystal Black, Golden Bee, Pure Red Line and the Taiwan Bees all belong to the same species group and crossbreed freely. Mixing them produces offspring with unpredictable patterns and lower grades. To keep a line true, keep one variety per tank, and remove off-pattern babies from your breeding group. Neocaridina won't crossbreed with Caridina, but they need harder water, so we don't recommend keeping them together.
Grades
Crystal Red and Crystal Black shrimp are graded by how much white they show and how clean the pattern is. Lower grades (S, SS) have more color and banding, higher grades (SSS and above) show more solid white. Grade affects looks and price, not care: every grade needs the same water.
Troubleshooting
- Losses in a new tank: almost always a tank that wasn't fully cycled or mature, or too many shrimp added at once. Give new setups the full 8 weeks, wait for the nitrate spike, and add shrimp gradually.
- 1–2 shrimp dying every day while the water tests perfect: in an older tank, this usually means waste has built up in the soil. Move the shrimp you can to another tank (set up with old tank water, plants and filter), carefully siphon the soil clean, and do a large water change. Anything under 30% won't help. If shrimp keep dying after that, the only fix is to reset the tank.
- Failed molts: a shrimp dead with its old shell still attached means a molting problem. Check GH and raise it slowly to 4–6 with remineralizer, focusing on GH rather than TDS.
- Shrimplets not surviving: usually not enough biofilm. A more mature tank, weekly baby powder and foods that promote biofilm all help.
- Losses after a water change: the new water didn't match. Check TDS, GH and temperature before every change, and change water only when nitrate calls for it.
- Heat: above about 84°F Caridina get stressed and stop moving around. Watch the tank in summer.
- Hydra: tiny white tentacled pests, almost always brought in on plants or moss. Treat with a fenbendazole dewormer (sold as Panacur C), which is safe for shrimp.
- Copper and chemicals: no copper-based medications, fertilizers or fittings, and no bug sprays or flea treatments near the tank.
- Resetting a tank: remove the shrimp, siphon out the old soil or clean it with 2–3 full water changes until the water runs clear, add a few cups of fresh soil (we use about 4 cups for 20 gallons) so the bacteria have ammonia to feed on, and cycle again from step 1. Don't top up an old soil bed with new soil to "revive" it; cleaning the soil works better.
A well-run Caridina tank can last for years: our oldest has been running since 2015.
Quick answers
Can I use tap water? No. RO/DI water with a Caridina remineralizer is a must; it's the only way to keep TDS and GH low and steady.
Are Caridina good for beginners? They are a good second step. Keep Neocaridina first, then move to Caridina once you have a stable tank and a TDS meter.
Do I need special soil? Yes. Active soil keeps the pH low and KH at 0. We use ADA Amazonia.
Do I need a lid? No. We don't use lids on any of our shrimp tanks.
Can I run CO2? Yes, gently: stay under about 3 bubbles per second.
How long do they live? About 1.5–2 years, and a healthy colony keeps going with new generations.
Ready to start? See our Caridina shrimp and moss and plants. Shipping and our live arrival guarantee are on the Shipping / DOA page.