Botanicals
Catappa Bark
Strips of Indian almond tree bark that release tannins, lower pH, and produce biofilm — a functional botanical with a naturalistic presence shrimp use actively.
Catappa bark is the stripped inner bark of the Indian almond tree (Terminalia catappa) — the same source as catappa leaves, concentrated into a slower-releasing, longer-lasting form. Submerged in the aquarium, the bark leaches tannins and humic acids into the water column gradually, softening water, lowering pH incrementally, and producing the amber-tinted, blackwater quality that Caridina shrimp and other soft-water species thrive in. The bark surface develops a rich biofilm layer as it conditions in the tank, creating a foraging surface that Neocaridina, Caridina, and snails graze methodically and continuously. It softens and breaks down slowly over several weeks to months depending on tank conditions, holding its structure and function significantly longer than catappa leaves — and when it does eventually break down, the decomposing bark becomes a substrate-level foraging resource in its own right. Safe for all shrimp, invertebrates, and fry.
What to Expect
What It Does in the Tank
Releases tannins and humic acids slowly and steadily — catappa bark conditions the water more gradually than catappa leaves, making it better suited to tanks where a consistent tannin contribution over an extended period is more useful than a rapid initial release. The tannin output tapers progressively as the bark ages, giving it a gentler, more sustained effect on water chemistry than leaf-based botanicals of equivalent size.
Lowers pH incrementally in soft, low-KH water — the tannins and humic acids released by catappa bark contribute to pH reduction in tanks with low carbonate hardness where the buffering capacity is limited. In tanks with significant KH the effect on pH is minimal — the tannins are consumed by the buffering capacity before they can lower pH measurably. Most impactful in soft-water setups specifically maintained for Caridina or blackwater species.
Produces amber water tinting without heavy discoloration — at typical use quantities, catappa bark produces a light amber tint rather than the deep brown associated with heavy botanical loads. The tinting is aesthetically consistent with natural blackwater and peat-influenced habitats and is considered desirable in shrimp and biotope tanks. It can be reduced or eliminated by running activated carbon, though this also removes the water conditioning benefits.
Develops a rich biofilm layer that shrimp graze actively — the bark surface accumulates biofilm within days of submersion, and shrimp colonize it quickly and graze it persistently. The textured, fibrous bark surface holds biofilm more effectively than smooth surfaces and continues producing new biofilm as older layers are grazed away, creating a self-renewing foraging resource that remains active throughout the bark's time in the tank.
Breaks down slowly — significantly longer than catappa leaves — the denser structure of bark means it holds its physical form for weeks to months rather than the one to three weeks typical of catappa leaves. Larger, thicker pieces last longest. As the bark softens and eventually begins to break apart, the decomposing material becomes substrate-level foraging territory that shrimp and snails work through thoroughly.
Pairs naturally with catappa leaves and other botanicals — bark and leaves from the same tree release the same tannin compounds and complement each other in the tank without competing chemically. Using both together produces a layered botanical environment — leaves at the substrate level breaking down more rapidly, bark at mid or substrate level conditioning more slowly — that more closely replicates the varied decomposition stages of a natural forest stream floor.
How to Use It
Getting Started
1
Rinse before adding to the tank — rinse the bark pieces under cool running water before use to remove loose surface debris and dust from storage and shipping. A brief rinse is sufficient — extended soaking or boiling is not necessary and will remove some of the beneficial tannins before the bark even enters the tank.
2
Sink or anchor as needed — fresh catappa bark may float initially before becoming fully waterlogged. Wedging pieces under a small stone, tucking between hardscape elements, or simply allowing a few days for the bark to absorb water and sink naturally are all effective approaches. Avoid forcing it to the bottom in ways that damage the bark structure.
3
Start with a modest quantity and observe — the tannin release from catappa bark is gradual but cumulative. Start with one or two pieces in a standard shrimp tank and observe the water tint and any parameter shifts over the first week before adding more. Tanks with very low KH respond more noticeably to tannin input than buffered tanks — calibrate accordingly.
4
Replace when fully broken down or leave as substrate foraging — once the bark has softened to the point of breaking apart, either remove and replace with fresh pieces or leave the decomposing material as substrate-level foraging territory. Shrimp and snails will continue working through the softened bark for some time after it loses structural integrity. There is no urgency to remove it.
💡 Bonus Tip
Catappa bark is one of the most effective botanicals to use during a Caridina tank setup before shrimp are introduced — adding bark to a cycling tank allows the tannin conditioning to build gradually over several weeks, so by the time parameters are stable and shrimp-ready, the water already has the amber tint, softened chemistry, and established biofilm surfaces that Caridina respond to best on introduction. Starting from a conditioned tank produces noticeably better initial acclimation than introducing shrimp to a freshly set up, botanically bare environment.
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Browse more botanicals
Pair Catappa Bark with Catappa Leaves, Alder Cones, or other botanicals for a complete blackwater setup. Browse our Botanicals collection.
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