Crystal red shrimp

Read this before anything else

Crystal reds cannot be kept on San Diego tap water. They need soft, acidic, low-mineral water — GH 4–6, KH at or near zero, pH 5.8–6.5, TDS 100–130 — and our tap is hard and buffered. The setup is RO or distilled water, remineralised with a GH-only product, over an active buffering aquasoil.

Full detail on the water side is on the Caridina page.

The grading scale

Crystal reds are graded on white coverage and opacity. From lowest to highest:

Buy A or S for a first colony. Grade is purely cosmetic; it says nothing about health. The higher grades are more heavily inbred, which tends to mean smaller broods and a narrower gene pool. An A grade colony will breed more reliably, cost far less, and teach you the same lessons. You can always select upward later from your own stock.

Crystal black shrimp are the same animal with black in place of red, graded identically, and kept identically.

The mistakes that kill colonies

Adding them too early

Fresh aquasoil leaches ammonia for two to four weeks, and the biofilm they graze takes longer than that to establish. Six to eight weeks from setup to first shrimp. This is the most common failure and it is entirely avoidable.

Using the wrong remineralizer

GH+KH products add carbonate hardness, which fights the soil's attempt to acidify the tank. Buy GH-only. The bottle will say so.

Chasing numbers

Once the tank is stable, the worst thing you can do is keep adjusting it. Small regular water changes with correctly mixed water, consistent temperature, no sudden dosing. Caridina die from change far more than from any particular value.

Letting the soil exhaust quietly

Active soil buffers for roughly eighteen months to three years. When it stops, pH climbs, breeding stops and nobody notices for weeks because nothing dramatic happens. If an established colony stops producing, test pH before anything else.

Breeding and hybridising

Females carry eggs for three to five weeks and release fully formed miniature shrimp. Broods are smaller than Neocaridina — twenty to thirty is typical rather than forty or fifty — and growth is slower.

Crystals interbreed with other Caridina cantonensis lines, including taiwan bees and tigers. Crossed with taiwan bees you get mischlings, which look like ordinary crystals but carry hidden recessive genes. Crossed with tigers you get tibees. This is how much of the modern range was made, and also how a deliberately bought line becomes a mixed bag. Decide what you are keeping before you stock.

They will not cross with Neocaridina — different genus.

Bring us your numbers

Free water testing at both stores, and for Caridina it is worth using. Bring a sample of your mixed water — the RO plus remineralizer you intend to use — rather than tap, and a TDS reading if you have a meter. Getting the mix right before the tank is running is far cheaper than diagnosing it afterwards.

Remineralizers and soils: shrimp supplements and substrates.

Questions we get asked

What grade of crystal red shrimp should I buy first?

A or S grade. Grading is purely cosmetic and the higher SS and SSS grades are more heavily inbred, which tends to mean smaller broods. An A grade colony breeds more reliably and costs far less.

Can crystal red shrimp live in tap water?

Not in San Diego. They need soft acidic water at GH 4 to 6 with almost no carbonate hardness, and local tap water is hard and buffered. RO water plus a GH-only remineralizer over active soil is the standard setup.

How long before I can add crystal reds to a new tank?

Six to eight weeks. Fresh aquasoil releases ammonia for the first two to four weeks and the biofilm they feed on takes longer still to establish.

Why has my crystal red colony stopped breeding?

Check pH first. Active soil exhausts after roughly eighteen months to three years, and when it does the pH climbs out of range and breeding quietly stops. Temperature running too warm is the other common cause.

What is a mischling?

The offspring of a crystal shrimp crossed with a taiwan bee. They look like ordinary crystals but carry hidden recessive genes, which is why they are sold separately and why mixing Caridina lines unintentionally causes problems.

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