Moneywort in Aquariums: Bacopa vs Lysimachia Guide

If you searched "moneywort" and ended up more confused than when you started, that's not your fault. The name gets slapped on two completely different plants, and pet stores rarely explain which one is in the bag. This guide sorts out the mix-up and gets the right moneywort growing in your tank fast.

Quick Answer: "Moneywort" usually means one of two plants: Bacopa monnieri, a true aquarium plant, or Lysimachia nummularia, a bog/pond plant sold as "creeping Jenny." Bacopa monnieri handles full submersion and moderate light; Lysimachia nummularia struggles underwater and does best in paludariums or pond margins. Check the leaf shape before you buy — round, coin-like leaves mean Lysimachia, while thick oval leaves in pairs mean Bacopa.

Why "Moneywort" Confuses So Many Fish Keepers

The name "moneywort" is a common-name trap, not a species name. If you've bought a plant labeled this way and it's melting in your tank, you may have the wrong species for underwater life.

Common names get recycled across totally unrelated plants all the time. Two of the biggest offenders here are Bacopa monnieri and Lysimachia nummularia. Only one of them is built for full submersion.

Bacopa monnieri, the same species studied in some herbal-supplement research for its bioactive compounds, is also widely sold as a true aquatic stem plant [2]. Lysimachia nummularia, on the other hand, is a creeping ground cover that tolerates wet soil but not permanent underwater life.

Pro Tip: If your pet store tag just says "moneywort" with no scientific name, ask to see the plant's root system. Bacopa has fine, hair-like roots along the stem; Lysimachia has thicker, fibrous roots meant for soil, not gravel.

Getting the ID right before you buy saves you a wasted trip and a dead plant two weeks later. That's the whole point of this guide.

Bacopa Monnieri vs Lysimachia Nummularia: How to Tell Them Apart

Bacopa monnieri is the aquarium-safe moneywort; Lysimachia nummularia is the pond and paludarium one. Mixing them up is the single most common mistake beginners make when shopping for "moneywort."

Bacopa has small, thick, oval leaves growing in opposite pairs along a sturdy stem. It stays fully green underwater and can grow 6-12 inches tall in a planted tank.

Lysimachia nummularia has round, flat leaves that look like tiny coins — hence "moneywort." It's a creeping, low-growing plant that spreads along damp soil rather than climbing upward in water.

Here's a side-by-side breakdown to settle the confusion for good:

Common Myth: "Moneywort is one plant, and any moneywort works in a fish tank." Reality: Only Bacopa monnieri is reliably aquatic. Lysimachia nummularia is more accurately a bog and pond plant sold under the same nickname.

If your tank is a standard glass box with fish swimming full-time, you want Bacopa monnieri. For a paludarium, riparium, or backyard pond, Lysimachia nummularia is the better fit — the full Lysimachia moneywort care guide covers that setup in depth.

Is Moneywort Invasive? What the Research Says

Lysimachia nummularia is classified as invasive in parts of North America, but Bacopa monnieri is not. This is one of the most-searched moneywort questions, and the answer depends entirely on which species you're holding.

Lysimachia nummularia spreads aggressively in wetlands and along stream banks once it escapes cultivation. Several state extension offices list it as a species to avoid releasing into natural waterways [1].

Bacopa monnieri behaves very differently in a home aquarium. It grows fast in a closed tank, but it doesn't survive long outside water in most climates, which limits its escape risk.

Here's what that means for your setup, in practice:

• Never release either plant into local ponds, lakes, or streams.
• Trim Bacopa monnieri regularly so trimmings don't clog your filter.
• Keep Lysimachia nummularia contained to pots if you're using it in a pond feature.
• Compost or bag plant trimmings instead of tossing them outside.

Pro Tip: If you're not sure which species you have, treat it as potentially invasive and dispose of trimmings in household trash, not a compost pile near open water.

As of 2026, most regional extension programs still flag Lysimachia nummularia as a watch-list species [1]. Bacopa monnieri remains widely sold and unrestricted in the aquarium trade.

Setting Up Moneywort in Your Tank the Right Way

Bacopa monnieri needs moderate light, soft-to-medium water, and a nutrient-rich substrate to thrive. Get those three things close to right, and the plant does most of the work itself.

Aim for water temperatures between 72-82°F and a pH range of 6.0-7.5. These parameters overlap with most community fish setups, so you rarely need a separate tank just for the plant.

A layer of nutrient-rich substrate, like Fluval Stratum on Amazon, gives roots something to grip and feeds the plant from below. Root tabs work too if you're using plain gravel.

New to planted tanks and not sure where to even start? Check out our complete beginner's guide to planted freshwater setups →

Light matters more than most beginners expect. Bacopa monnieri does fine under moderate LED lighting for 8-10 hours a day, but weak light causes leggy, sparse growth with long gaps between leaves.

A liquid fertilizer like Seachem Flourish helps fill nutrient gaps, especially in tanks without root tabs. Dose weekly, following the bottle's instructions for your tank size.

Planting and Trimming Basics

Plant stems in small groups of 3-5 rather than single sprigs. This creates a fuller look faster and helps the plant establish roots more reliably.

• Trim the top 2 inches once the stem reaches your desired height.
• Replant healthy cuttings to fill in bare spots.
• Remove yellowing or mushy leaves right away to prevent rot spreading.

Common Mistakes When Growing Moneywort

The number one mistake is buying Lysimachia nummularia expecting it to thrive fully submerged. It usually melts within a few weeks, leaving beginners thinking they killed a "beginner plant."

The second common mistake is planting Bacopa monnieri too deep in the substrate. Bury only the bottom node or two — burying the whole stem section causes stem rot instead of root growth.

A third mistake is skipping water testing entirely. A kit like the API Freshwater Master Test Kit helps you confirm your pH and hardness actually match what the plant needs.

Here's a quick troubleshooting list for struggling moneywort:

1. Leaves turning black and mushy — likely Lysimachia struggling underwater; move it emersed.
2. Leggy, thin stems with wide leaf gaps — not enough light; increase duration or intensity.
3. Slow or stalled growth — add root tabs or liquid fertilizer.
4. Stem rot near the base — planted too deep; replant shallower.

Pro Tip: If you're trying to keep costs down while fixing a struggling planted tank, start with fertilizer and lighting fixes before buying new substrate — they're the cheapest changes with the biggest impact.

Tankmates and Companion Plants for Moneywort

Bacopa monnieri pairs well with community fish that won't shred its soft leaves. Species that graze lightly on algae rather than tearing through plant matter are the safest bet.

Peaceful community fish like tetras, rasboras, and corydoras rarely bother established Bacopa. Some keepers also pair it with the American flagfish (Jordanella floridae), a hardy species known for grazing algae off leaves without destroying the plant itself [3].

Avoid heavy plant-eaters like large goldfish or silver dollars in a Bacopa-focused tank. They'll strip the stems faster than the plant can regrow.

For companion planting, mix Bacopa with foreground plants that won't compete for the same light layer:

• Dwarf hairgrass for a lawn-like foreground
• Java fern attached to driftwood for a mid-ground layer
• Anubias nana for low-light corners near the substrate

Everything your first planted community tank needs, in one checklist — see our full planted tank starter guide →

Conclusion

"Moneywort" hides two very different plants behind one nickname. Bacopa monnieri belongs in your fish tank; Lysimachia nummularia belongs in a pond edge or paludarium.

Check the leaf shape before you buy, match the plant to your setup, and trim regularly to keep growth healthy. Since early 2026, aquarium retailers have started labeling species names more clearly, but it's still worth double-checking before checkout.

Sources

1. https://ask.extension.org/kb/faq.php?id
2. https://pubmed.ncbi.nlm.nih.gov/29798681/
3. https://www.seriouslyfish.com/species/jordanella-floridae/