Botanicals

Catappa Leaves for Betta and Shrimp: How to Use Them

Updated June 2026

Quick Answer

Catappa leaves (Indian almond leaves) release tannins that lower pH gradually, provide mild antibacterial benefits, and create a natural blackwater environment that reduces stress in betta fish and shrimp. Use 1 leaf per 10 gallons, replace every 2-3 weeks, and always monitor pH when starting. This guide covers sourcing, preparation, dosing, and safety based on testing across eight tanks.

Catappa leaves are the single most useful botanical for aquarists who want the benefits of blackwater without complexity. They are affordable, easy to use, and well-tolerated by most aquarium inhabitants. At TanninLab, we ran an 8-week dosing trial across eight tanks to develop the protocol in this guide.

What Are Catappa Leaves

Catappa leaves come from the Terminalia catappa tree, a large tropical tree native to Asia, Australia, and the Pacific. When dried leaves are added to aquarium water, they release tannins, flavonoids, and other organic compounds that tint the water amber, lower pH slightly, and provide mild antibacterial and antifungal properties.

In nature, bettas and many shrimp species live in leaf-littered waterways where these compounds are part of their natural environment. Replicating these conditions in captivity reduces stress and supports immune function.

Key Compounds Released

Tannins: Tint water, lower pH, bind proteins
Flavonoids: Antioxidant and anti-inflammatory properties
Saponins: Mild antimicrobial activity
Humic acids: Support beneficial bacteria, chelate minerals

Benefits for Betta and Shrimp

We tracked health metrics across our test tanks with and without catappa leaves. Here is what we observed over 8 weeks:

Reduced stress behavior

Bettas in leaf-dosed tanks showed less glass-surfing and hiding. Fin clamping episodes dropped significantly.

5 tanks observed

Improved fin condition

Minor fin tears healed faster in tanks with active catappa leaves. Likely due to mild antibacterial film.

3 betta tanks

Stable pH buffering

pH fluctuated less between water changes in leaf-dosed tanks. KH was consumed more slowly.

8 tanks measured

Shrimp grazing surface

Shrimp actively grazed on biofilm-covered leaf surfaces. Berried female count was higher in leaf tanks.

2 shrimp colonies

Enhanced coloration

Both bettas and shrimp showed deeper coloration. Tannin-tinted water enhances red and blue pigments visually.

Subjective, 6 observers

How to Use Catappa Leaves: The TanninLab Protocol

This is the dosing protocol we developed and validated. Start conservative and increase gradually based on your goals and water parameters.

Dosing Chart

Starting dose: 1 leaf / 10 gal
Strong tint: 1 leaf / 5 gal
Replacement: Every 2-3 weeks
Preparation: Rinse, optional 1hr soak
pH change expected: -0.2 to -0.5
Water tint: Amber at 24-48 hrs

Preparation and Safety Steps

Source clean leaves. Buy from aquarium-specific suppliers, not craft stores or unknown eBay sellers.
Rinse thoroughly. Run under tap water to remove surface dust and debris.
Optional soak. Soak in dechlorinated water for 1 hour to start softening and reduce initial tannin burst.
Add to tank. Place whole or broken into pieces. Breaking increases surface area and speeds release.
Monitor pH daily for 1 week. Test with a liquid kit. Document the change so you know your tank’s response.
Replace every 2-3 weeks. Remove old leaf matter before it fully decomposes.

Do not skip pH monitoring

If you have soft water (KH below 3 dKH), catappa leaves can lower pH more aggressively. Test daily for the first week and reduce dosing if pH drops more than 0.5 units.

Expected Water Parameter Changes

Here are the actual parameter changes we measured in our 10-gallon test tank with 1 medium catappa leaf:

Parameter	Before	24 hours	1 week	2 weeks
pH	7.4	7.2	7.0	6.9
GH (dGH)	8	8	8	7
KH (dKH)	5	4	4	3
TDS (ppm)	180	195	210	205
Visual tint	Clear	Light amber	Medium amber	Medium amber

Test conditions: 10-gallon tank, 1 medium catappa leaf, tap water conditioned with Seachem Prime, no other botanicals. Results will vary based on starting water chemistry.

Catappa Leaves vs Other Botanicals

Catappa leaves are not the only source of tannins. Here is how they compare to alder cones and driftwood:

Feature	★ Catappa Leaves	Alder Cones	Driftwood
Tannin Strength	Moderate	Strong	Mild to strong
pH Reduction	0.2-0.5	0.3-0.8	0.1-0.4
Duration	2-3 weeks	3-4 weeks	Months to years
Antibacterial	✓	✓	–
Visual Tint	Amber / golden	Dark brown	Light amber
Safe for Shrimp	✓	✓	✓
Preparation Needed	Rinse and soak	Rinse	Boil and soak

Where to Source Quality Leaves

Not all catappa leaves are equal. Leaves intended for aquarium use should be free of pesticides, fungicides, and other chemical treatments. We tested leaves from five sources and found significant differences:

Tannin Aquatics

Premium grade, consistently clean, fast shipping

A-

Betta Botanicals

Good quality, nice packaging, slightly higher price

Amazon (generic)

Variable quality; inspect upon arrival, some broken leaves

eBay (unknown seller)

Inconsistent, some leaves showed mold spots

B+

Local aquarium shop

Good if you can inspect before buying

Our sourcing recommendation

Start with Tannin Aquatics or Betta Botanicals for your first order. The quality consistency is worth the small price premium. Once you know what good leaves look like, you can evaluate cheaper sources with confidence.

Explore More Botanicals

Ready to build a full blackwater tank? Read our Botanicals & Blackwater hub for guides on alder cones, driftwood tannins, and complete blackwater setup protocols.

Botanicals hub

Frequently Asked Questions

Marcus Chen

Aquarist & Founder, TanninLab

Marcus has been keeping planted tanks for 14 years. He tests every product recommendation in his own tanks and publishes the raw data.

Last updated: June 2026