Kiriwel Bark | Ichnocarpus frutescens
Kiriwel Bark on the Surface:
Kiriwel Bark is a medium-tannin, fibrous bark of Ichnocarpus frutescens, a woody climbing liana found across the forested understories of Southeast Asia, India, and northern Australia. Ours is sustainably collected for us by hand and gently sun-dried in Sri Lanka for the Botanical Method, blackwater, and biotope aquarium. Because of its fibrous and high-lignin composition, this aquarium bark holds its structure for months, providing long-term biofilm and encrusting algae growth sites, and helping create interstitial pore space on the substrate for small fish and microfauna. Our favorite way to use it is layered into the leaf litter bed for substrate diversity, though it can also be superglued to manzanita or larger wood to replicate peeling bark.
Essential Details
- Tannin Level: Moderate
- Tint Color: Amber to deep brown
- Durability: High; lasts for months
- Habitat Location: Sri Lanka
- Optimal For: shrimp, otocinclus, corydoras, cherry barbs, betta fish, apistogramma, rasboras, plecos, frogs, and isopods
- Use with Caution: No known concerns for standard aquarium inhabitants
- Size Range: 1 to 5 inches
- Quantities: ~40 grams of Ichnocarpus frutescens Bark per pack
Kiriwel Bark for Aquariums & Vivariums
Once added to the aquarium, Kiriwel Bark begins cultivating biofilm and fungal growth across its fibrous surface, an extracellular microbial community that shrimp, otocinclus, and bottom-dwelling fishes consume as supplemental nutrition. Its rough external fibers provide ideal surface areas, allowing the biofilm and fungi to spread into the interstitial pore space between the bark folds.
Kiriwel Bark functions as a structural botanical, contributing to the aquarium over a longer period than more ephemeral materials like leaf litter. As it conditions on the substrate, it releases tannins and a complex of polyphenols, including gallic, caffeic, and ferulic acids, into the water column. These compounds contribute to the organic chemistry of the habitat over weeks and months, which is why it is best to let the bark fully break down on the substrate. We recommend adding Kiriwel Bark as a recurring input rather than a single addition, building substrate continuity that sustains the microbial food web as older cellulose fibers convert to beneficial detritus.
In a vivarium, the fibrous composition of Kiriwel Bark makes it a nutritious substrate for springtails, isopods, and other clean-up crew members. There is no need to remove it once it has fully broken down, as the detritus and mulm it creates feeds the network of bacteria and fungi working beneath the leaves.
Beneath the Leaves: Ichnocarpus frutescens in the Wild
Ichnocarpus frutescens is a slender, winding liana that sprawls over ten meters through coastal forests and open woodlands, from India and Sri Lanka across Southeast Asia to northern Australia. It carries lush leaves up to eleven centimeters long, clusters of small flowers with densely hairy sepals, and elongated fruit pods that mature past fourteen centimeters. As a component of the forest understory, it sheds bark and leaf debris into the organic litter on the floor below, where seasonal rains carry that material into the streams and flooded river margins where blackwater fishes live. In its native Sri Lanka, those streams hold endemic species like the cherry barb (Puntius titteya) and the pearl rasbora (Rasbora vaterifloris), a fish documented among submerged leaf debris in cool, heavily shaded forest water. Ichnocarpus also carries a long history of medicinal use across South and Southeast Asian traditions, and the same gallotannins, flavonoids, and phenolic acids that define those uses are present in the bark tissue and passively released as it breaks down. How these compounds interact with the ecosystem at aquarium scale has not been studied, but their presence places Kiriwel Bark within the same chemistry that shapes wild blackwater habitats.
It's tough, lignin-rich fibers cultivate a slightly different assemblage of bacteria and fungi than leaf litter or seed pods do, and this material diversity helps stabilize the ecosystem in your home aquarium. When we add Kiriwel Bark into the aquarium, we replicate the allochthonous inputs that fuel the food webs of aquatic ecosystems around the globe. Mother Nature leads the way.
Sustainability Note:
This product's packaging is home compostable.
Just like the botanicals inside, it will break down naturally and return to the soil — because what supports your ecosystem should minimally impact our planet.
Not for human consumption. Preparation required.
This is a natural product — variation in color, shape, and texture is expected.
Kiriwel Bark | Ichnocarpus frutescens
Home is getting more natural
While the aesthetic appeal of botanicals and tinted water can be quite attractive to us, the recreation of nature to emulate water conditions, feeding patterns, spawning displays, and territory building are the true benefits botanicals provide to our critters.
Botanical FAQs
Compostable Packaging Promise
Our packaging is designed to return safely to the Earth, just like the botanicals inside. Every bag is BPA- and Phthalate-free, GMO-free, and contains no animal products. Each meets ASTM D6400 composting standards, ensuring it can fully break down in a home compost bin.
What are the Fluffy White Growths on my Botanicals?
That’s biofilm and fungi—what we call the “goo phase.” It’s one of the clearest signs that your aquarium is alive and functioning. These growths wax and wane naturally as botanicals decompose. They’re harmless, even beneficial, and will disappear on their own once microbial populations stabilize.
Will botanicals lower the pH of my water?
That depends entirely on your source water. In very soft or RODI water, botanicals can gradually lower pH as tannins and humic substances accumulate. In medium to hard tap water, buffering capacity often resists these shifts, and you may not notice much change. At Betta Botanicals HQ, our very hard water (350+ ppm) shows almost no pH change unless we use botanicals like Alder Cones or Macaranga Leaves.
When should I replace leaves or pods in my tank?
We recommend allowing botanicals to fully break down into detritus, since this fuels microbial life and enriches the substrate. You can remove them once they stop tinting the water, but you’ll lose some of their ecological benefits. Each time you add new botanicals, follow proper preparation and observe your livestock until you learn your aquarium’s rhythm.
Are your products just for bettas?
Nope. Our botanicals are safe for almost all aquariums, terrariums, vivariums, and paludariums. The only exceptions are goldfish and axolotls, which may ingest small pods like alder cones or casuarina cones. For those species, we recommend large leaves such as Indian Almond, Loquat, or Jackfruit.
What are Tannins?
Tannins are natural compounds released by leaves, seed pods, and bark as they decompose in water. They soften water, gently lower pH, and create the characteristic tea-stained tint found in blackwater habitats. But their role goes far beyond color—tannins fuel beneficial bacteria, fungi, and biofilms, which form the foundation of a healthy ecosystem. They also offer mild antifungal benefits and help reduce stress in fish by replicating the natural conditions they’ve evolved in. At their core, tannins are plant-derived antioxidants that connect your aquarium to the same processes at work in wild flooded forests and streams.