Cholla Wood for Shrimp Tanks: What It Is and How to Use It

Walk into any serious shrimp breeder's fish room and you'll find the same thing in every tank: a few hollow, holey tubes of pale wood with shrimp crawling in and out of them. That's cholla wood, and it's about the cheapest, most useful piece of hardscape you can add to a shrimp tank. It grows biofilm, it gives molting shrimp and shrimplets somewhere to hide, and it costs a few dollars a piece.

It also floats for two days, grows a coat of white fuzz in its first week, and dissolves into mush within a year or two, all of which send new keepers to forums asking whether something's gone wrong. Nothing has. This guide covers what cholla wood for shrimp actually is, why it works, how to prepare it, how long it lasts, and where to get it without gambling on a craft-store mystery stick.

Moss on driftwood in a planted tank. Cholla is lighter and hollow, but it does the same job: surface for biofilm, cover for shrimp

Quick Answer

Cholla wood is the dried woody skeleton of a cholla cactus, genus Cylindropuntia, from the deserts of the southwestern United States and Mexico. It's a hollow tube full of holes, which makes it a shelter for shrimp and a surface that grows biofilm, the bacteria and microorganism film that dwarf shrimp graze on all day. Rinse it, boil it for a few minutes or soak it until it sinks, and drop it in. It releases mild tannins, grows harmless white fuzz for a few weeks, and breaks down over months to a couple of years depending on the piece. Buy it from an aquarium or shrimp retailer, not a craft store, so you know it hasn't been treated.

What Cholla Wood Actually Is

Cholla wood isn't wood from a tree. It's what's left when a cholla cactus dies and dries out. Chollas are the genus Cylindropuntia, cacti with cylindrical rather than paddle-shaped stems, native to the southwestern US and northern Mexico. Wikipedia counts roughly 35 species and notes that "dried, dead Cylindropuntia sections are called 'cholla wood' and are popular in the pet trade." The Shrimp Farm's guide describes it the same way: the wooden skeleton that remains after the cactus dies and dries.

The living cactus has a lattice of woody tissue running through its stem. When the fleshy green outside rots away, that lattice is what's left: a light, hollow cylinder with a fibrous surface and a pattern of holes along its length. Bantam Earth's driftwood guide names Cylindropuntia fulgida, the jumping cholla, as a common source, and Wikipedia lists it alongside Cylindropuntia imbricata, the cane cholla, as the best known species.

Pieces sold for aquariums are usually cut to 4 to 6 inches and about an inch across. Tannin Aquatics, a botanicals supplier, describes collecting only downed, dead skeletons from public land, which is the norm for the trade. Nobody is cutting live cacti for this.

Why Shrimp Keepers Use It

Three reasons, and all three come up in every retailer's description.

Biofilm. This is the big one. As cholla sits in water it softens and starts to break down, and a film of bacteria, fungi, and microalgae grows over every surface, inside and out. Flip Aquatics describes the wood as surface area for biofilm growth and calls it a natural feeding ground; The Shrimp Farm says the same, noting that biofilm "is one of their favorite foods." For adults it's a snack bar. For shrimplets in their first weeks, when they can't compete for pellets and need grazing within an inch of cover, it's often the difference between a clutch surviving and disappearing. Our how to raise shrimplets guide leans on this heavily.

Cover. A hollow tube with holes in it is a ready-made shrimp cave. Shrimp Up Aquatics sells it specifically as shelter for shrimplets, and The Shrimp Farm points out when it matters most: right after a molt, when the new shell is soft and the shrimp needs to hide for a day or two. Post-molt stress is when most losses happen, as our shrimp molting guide explains.

Tannins. Cholla leaches a small amount of tannin as it breaks down. Flip Aquatics, The Shrimp Farm, and Teacher's Pet all compare the effect to Indian almond leaves: a light tint and mild antibacterial and antifungal properties. Tannin Aquatics, who sell it for exactly this, say it leaches "a small amount," and that's the honest framing. It's a bonus, not a substitute for leaves.

Cholla Wood vs Driftwood vs Leaves

Cholla isn't better than driftwood or botanicals; it does a different job. Here's how the three compare in a shrimp tank:

The usual combination is a piece of driftwood as permanent structure, cholla tucked around it for shrimplet cover, and a leaf or two for tannins. Our Indian almond leaves for shrimp guide covers the leaves.

How to Prepare Cholla Wood

Dry cholla floats. That's the only real preparation problem, and there are two ways to solve it.

◆Rinse first

Rinse the piece under the tap and pick out any loose debris from the holes. Bantam Earth notes the porous structure traps debris and recommends a light brush; a bottle brush through the hollow works well.

◆Option 1: Boil it

Boiling waterlogs the wood so it sinks right away, kills anything living on it, and pulls out the first rush of tannins. How long to boil is where sources scatter:

Five to ten minutes is plenty for a 4 to 6 inch piece. Longer boils pull more tannin but soften the wood; The Shrimp Farm's guide warns that boiling "does cause the wood to break down much quicker," which is why shrimp retailers keep it short and the botanicals seller chasing clear water goes long. Let it cool in the pot and it should sink when you drop it in. If it still bobs, a rock on top for a day finishes the job.

◆Option 2: Soak it

If you'd rather not boil, drop the rinsed piece in a bucket or straight into the tank. Flip Aquatics and Shrimp Up Aquatics both say 24 to 48 hours to sink, The Shrimp Farm's product page says about 48 hours, and Tannin Aquatics says a week or more for their pieces. Thickness is the variable: a thin 4 inch piece is down in a day, a fat log can take a week. Shrimp Up Aquatics suggests dumping the first soak water to cut the initial tannin release, and weighting the piece with a small stone if it keeps floating. Unboiled cholla releases tannins more gradually into the tank, which is fine, but don't drop three fresh pieces into a 5 gallon at once if you care about clarity.

◆Where to put it

Anywhere shrimp already hang out: near the sponge filter, half buried in moss, or leaning against driftwood. Leave the hollow open at both ends so shrimp can pass through, and don't bury it in substrate, which starves the inside of flow and turns the biofilm to sludge.

The White Fuzz Is Normal

A week after cholla goes in, you'll see a white, cottony coat growing on it, sometimes thick enough to look like the wood grew fur. This is the point where a lot of people pull it out and throw it away. Don't.

The fuzz is a mix of water mold and biofilm growing on the sugars leaching out of fresh wood. Teacher's Pet describes it as generally harmless to shrimp, The Shrimp Farm's guide calls the biofilm on cholla exactly what shrimp forage on, and keepers routinely watch shrimp and snails pick it clean. It shows up on every piece of fresh wood and botanical, not just cholla, and dies back on its own once the easy food in the wood is used up, usually within two to six weeks. Boiling shortens the fuzz phase because it pulls out some of what feeds it, but doesn't skip it.

How to tell it from real fungus or cyanobacteria, and how to speed it along, is in our white fuzz on driftwood guide. The short version: if shrimp are grazing it and nothing is dying, leave it.

How Long Cholla Wood Lasts

Not long, and sources disagree about how not long. That's because cholla is a soft, porous wood that breaks down at a rate set by temperature, flow, how many mouths are grazing it, and how thick the piece is.

Read that as: a standard 4 to 6 inch piece in a warm, busy shrimp tank is soft in six months and falling apart within a year or so, and a thick piece in a cool tank goes two years. The short 2 to 4 month figure from Shrimp Up Aquatics is worth taking seriously, since a colony of a hundred grazing shrimp eats cholla far faster than a tank with ten.

The wood doesn't fail all at once. It gets soft, the outside fibers shed, and eventually the tube collapses when you touch it. None of that hurts anything; the crumbs become mulm that snails and detritus worms finish off. Pull it when it's structurally gone, and drop in a new piece a couple of weeks before you remove the old one so the biofilm supply doesn't skip a beat. Treat cholla as a consumable you replace once or twice a year, like leaves, not hardscape you buy once.

Does Cholla Wood Lower pH?

A little, and less than people fear. Bantam Earth says it lowers pH and softens water, Teacher's Pet describes a slight pH reduction, and MarcusFishTanks says it slightly lowers pH, all from the tannins it releases. But Tannin Aquatics' "small amount" is the key phrase: a 6 inch piece leaches far less than a handful of leaves, and in a tank with measurable KH the buffer absorbs it. A Neocaridina tank on tap water is unlikely to register it on a test kit. A Caridina tank on RO water with near-zero KH has less buffer, so add a piece or two at a time rather than a pile, and measure before and after if you're chasing a specific number.

Where to Buy Cholla Wood (and What to Avoid)

Every shrimp retailer sells it. Flip Aquatics lists 4 and 6 inch pieces at $4.99 to $5.99, The Shrimp Farm sells 4 to 6 inch pieces for $5.99, and Shrimp Up Aquatics sells 6 inch pieces at $4 each with multipacks. Multipacks on Amazon bring the per-piece cost down further, and 12 inch logs there can be sawn into halves or thirds.

The thing to avoid is cholla from anywhere that isn't selling it for aquariums. Craft stores and floral suppliers sell it for decorating, reptile shops for perches, and hardware stores as garden accent. Some of it is probably fine, and forum keepers report using craft-store pieces without trouble, but you have no way to know. Aqua Rocks Colorado's guide on aquarium-safe wood puts it plainly: decorative wood from craft stores, floral displays, reptile decor, or home improvement stores "is not automatically safe just because it looks natural," and the treatment history "is often impossible to verify." Bantam Earth gives the same warning for hardware-store and wild-collected pieces, citing possible chemical treatments or pesticides. Shrimp die from a lot less than a fungicide-dipped stick.

If you live where chollas grow and want to collect your own, take only dead, fully dried skeletons well away from roads and sprayed land, and boil them. The Shrimp Farm's guide allows for this but notes the drying takes a long time, so skip anything with flesh still on it.

Getting More Out of It

A few tricks that make cholla work harder:

• •Tie moss to it. Java or Christmas moss wrapped around a piece turns a hiding spot into a grazing reef, and Bantam Earth notes the fibrous surface takes epiphytes readily. Our best moss for shrimp tanks guide covers which mosses stay put.
• •Seed it with a biofilm booster. A pinch of GlasGarten Bacter AE near a fresh piece gets the film established faster, which matters most in a new tank where shrimplets are due before the wood has seasoned.
• •Stack pieces. Two or three leaned into a loose pile give more interior cover than one big one, and you can pull a single seasoned piece to give a new or quarantine tank instant cover and instant food.

Frequently Asked Questions

◆Do I need to boil cholla wood before putting it in my shrimp tank?

No, but it helps. Boiling for 5 to 10 minutes sinks it immediately, kills anything on the surface, and shortens the white fuzz phase. If you skip boiling, rinse it and soak it for a day or two until it sinks, or weigh it down in the tank. Either way it's shrimp safe.

◆How long does cholla wood take to sink?

Boiled, it sinks as soon as it cools. Unboiled, most 4 to 6 inch pieces waterlog and sink in 24 to 48 hours, and thick pieces can float for a week. A small stone on top holds it down in the meantime.

◆Is the white fuzz on cholla wood bad for shrimp?

No. It's water mold and biofilm feeding on sugars in the fresh wood, and shrimp and snails eat it. It appears in the first week and clears on its own in two to four weeks. Only worry if it's blue-green and slimy (cyanobacteria) or if shrimp are dying, which points to a water problem, not the wood.

◆How long does cholla wood last in an aquarium?

Retailers quote anywhere from a few months to about two years. A standard 4 to 6 inch piece in a warm, well stocked shrimp tank is usually soft within six months and falling apart within a year. Treat it as a consumable and replace it, rather than expecting it to last like driftwood.

The Bottom Line

Cholla wood is a dead cactus skeleton that happens to be the perfect shrimp hide and biofilm farm, for about the price of a coffee. Rinse it, boil it for a few minutes or soak it until it sinks, ignore the white fuzz, and replace it when it goes soft. Buy it from a shrimp or aquarium retailer so you know it's untreated, pair it with a leaf or two, and your shrimplets have somewhere to hide and something to eat from the day they hatch.