Caridina — soft water, and real commitment

You cannot use San Diego tap water

This is the honest headline. Caridina want soft, acidic, low-mineral water — GH around 4 to 6, KH at or near zero, pH in the high 5s to low 6s. San Diego tap is hard and buffered, which is the opposite. There is no adjustment, additive or conditioner that turns our tap into Caridina water.

The standard setup is RO or distilled water, remineralised with a GH-only product, over an active buffering aquasoil that pulls pH down into the low 6s and holds it there. Every part of that sentence matters:

• GH-only, not GH+KH. Adding carbonate hardness fights the soil that is trying to acidify the tank, and the soil loses. GH+KH remineralizers are for Neocaridina.
• Active soil, not inert gravel. The soil is doing the buffering. When it exhausts — typically eighteen months to three years — pH climbs and the tank stops being a Caridina tank.
• RO, not tap. You are building the water from nothing so you know exactly what is in it.

Target parameters

Tiger shrimp (Caridina mariae) sit slightly outside this — they tolerate a touch more hardness and a pH nearer neutral, which makes them the sensible first Caridina for anyone stepping across from Neocaridina.

What the grades mean

Crystal red and crystal black shrimp are graded by how much white they carry and how opaque that white is. Working upward: C and B grades show thin, broken bands; A and S show cleaner, wider banding; SS and SSS show heavy solid white, often described by pattern names such as hinomaru, mosura and no-entry.

Grade is cosmetic. It is not a measure of health or hardiness — in fact heavily selected high grades are often a little less robust, because the same inbreeding that fixes the pattern narrows the gene pool. A tank of A-grade crystals is easier to keep and breeds more reliably than a tank of SSS, and for a first Caridina colony that is the better buy.

Taiwan bees

King kong, panda, blue bolt, wine red and the rest are recessive-gene morphs within the same Caridina cantonensis complex. They are the most demanding of the group and the least tolerant of parameter drift. They cross with crystals readily, and the offspring — often sold as mischlings — carry the recessive genes without showing them.

Hybridising

Caridina species interbreed with each other. Crystals crossed with tigers produce tibees, and those crossed back produce taitibees. This is how much of the modern range was created, and it is also how a carefully bought colony turns into something unrecognisable if you mix lines without meaning to. Decide what you want before you stock.

Patience is the actual requirement

The single most common Caridina failure is adding shrimp to a tank that is not mature. Fresh active soil leaches ammonia for the first two to four weeks; the biofilm that shrimp eat takes longer still to establish. A Caridina tank should be set up, planted, cycled and left alone for six to eight weeks before a single shrimp goes in. Neocaridina will forgive you for rushing. Caridina will not.

Once established, they are less fragile than their reputation suggests. Keep the parameters steady, change small volumes of correctly remineralised water on a schedule, do not overfeed, and a colony will run for years.

Everything else that applies

Copper is lethal — see the Neocaridina page for the full rundown, which applies identically here. Molting depends on mineral content. Biofilm is the real food. Drip acclimation matters more for Caridina than for anything else we sell, because they are reacting to TDS and you are usually moving them between two quite different waters.

For remineralizers, soils and the rest of the equipment, see shrimp supplements and substrates at Pet Zone.

Questions we get asked

Can I keep Caridina and Neocaridina in the same tank?

They will not interbreed, so there is no genetic risk. The problem is water: Neocaridina want hard buffered water and Caridina want soft acidic water, so any single tank is wrong for one of them. Keep them separately.

Do I really need RO water for crystal red shrimp?

In San Diego, yes. Our tap water is hard and buffered, which is the opposite of what Caridina need, and no additive converts it. RO plus a GH-only remineralizer over active soil is the standard approach.

Which Caridina is easiest to start with?

Tiger shrimp, then A or S grade crystal reds. Tigers tolerate slightly harder water and a pH nearer neutral. Taiwan bees such as blue bolts and king kongs are the least forgiving and are not a good first colony.

How long should I wait before adding Caridina to a new tank?

Six to eight weeks. Fresh aquasoil leaches ammonia for the first two to four weeks, and the biofilm they graze takes longer than that to establish. Rushing this is the most common way a Caridina colony fails.

Why did my crystal reds stop breeding?

Most often the soil has exhausted and pH has climbed, or temperature is running too warm. Check pH and TDS first; active soil typically buffers for eighteen months to three years before it needs replacing.

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