Is Quillwort a Good Plant for Redtail Splitfin?

Reviewed by Guidarium Editorial DeskUpdated May 11, 2026

Not Recommended

Quillwort is not recommended for Redtail Splitfin. The issue is practical, not cosmetic: their hardness ranges are too far apart for a reliable long-term match.

Quillwort

Isoetes lacustris

View plant profile

PlacementForeground

LightModerate

DifficultyIntermediate

Size15 × 10 cm

Redtail Splitfin

Xenotoca eiseni

View fish profile

TemperamentSemi-Aggressive

FamilyLivebearers

Temp18–26°C

Water TypeFreshwater Only

Quick Decision

A plant can be technically compatible with a fish and still fail in the actual tank if the fish digs, chews, needs denser cover, or uses a different part of the layout.

Overall fit

64/100

The fish is likely to outgrow, uproot, or out-pressure the plant.

Water match

Limited overlap

One or more core water ranges does not overlap cleanly.

Plant pressure

Moderate

Quillwort needs thoughtful placement and anchoring.

Layout value

Low cover

Quillwort helps with good refuge for shrimp and good grazing surface.

Plant and Fish Fit Notes

Use these signals to decide whether the plant is doing useful work for the fish, or whether it is only surviving beside it.

FactorQuillwortRedtail Splitfin

Temperature

Quillwort10-24°C

Redtail Splitfin18-26°C

Overlap: 18-24°C.

Quillwort5-7.5

Redtail Splitfin7-8.5

Overlap: pH 7-7.5.

Hardness

Quillwort1-8 dGH

Redtail Splitfin10-25 dGH

Overlap: No clean overlap.

Water and flow

QuillwortFreshwater Only, Moderate (Standard)

Redtail SplitfinFreshwater Only, Moderate (Standard)

Flow expectations are close enough for one layout.

Space used

QuillwortForeground and Midground

Redtail SplitfinTop (Surface) and Middle (Open Water)

Pressure signals

QuillwortHigh uproot resistance, Tough / leathery leaves

Redtail SplitfinSemi-Aggressive, Fin Nipper, Fry Predator, and Hyperactive / Fast Swimmer

Plant pressure: Moderate.

Planting value

QuillwortGood refuge for shrimp and Good grazing surface, Nutrient-rich substrate preferred

Redtail SplitfinPlants - Densely covered and Established Algae (Otocinclus)

Shared Tank Conditions

Quillwort and Redtail Splitfin do not share a clean environmental window, so the pairing is already under pressure before behaviour is even considered.

Both do best with moderate flow, so circulation does not need to be split into competing zones.

Both are suited to freshwater, so salinity does not add an extra planning problem.

Fish Pressure and Plant Resilience

Redtail Splitfin can still be rough on plants, but this pairing becomes more realistic when the plant is anchored well and used as part of a larger layout.

Quillwort has low cover density, high uproot resistance, and tough / leathery leaves. It can also help with shrimp refuge and grazing surfaces.

Quillwort is less tempting than softer, more palatable plants for known nibblers.

The limiting issue is their hardness ranges are too far apart for a reliable long-term match.

Layout Fit

Quillwort is a rosette / crown plant usually used foreground and midground.

Redtail Splitfin is a livebearer, so the pairing works best when the planting style supports how that fish uses space and cover.

Quillwort reaches about 15 cm tall by 10 cm wide and is usually rooted in substrate with nutrient-rich substrate preferred. That makes placement and anchoring more important than simply adding a larger bunch of stems or leaves.

In this pairing, the useful plant values are shrimp refuge and grazing surfaces. Place it where Redtail Splitfin can actually use that structure instead of hiding the plant where it cannot do much.

Practical Recommendation

For most keepers, a tougher or better-matched plant is the smarter choice. If you still try it, test with a small amount first and be ready to move the plant before it is badly damaged.

The decision should center on this signal: Their hardness ranges are too far apart for a reliable long-term match.

Best Use Case

Quillwort is usually the wrong plant for Redtail Splitfin if your goal is a stable display tank. The issue is rarely one dramatic failure on day one; it is the steady mismatch between what the fish does in the scape and what the plant needs to stay attractive long term.

Frequently Asked Questions About Quillwort and Redtail Splitfin

Is Quillwort a good plant for Redtail Splitfin?

Quillwort is not recommended for Redtail Splitfin. The issue is practical, not cosmetic: their hardness ranges are too far apart for a reliable long-term match.

Can Redtail Splitfin damage Quillwort?

Their hardness ranges are too far apart for a reliable long-term match.

No. The biggest issue is that their water conditions do not line up cleanly enough for a long-term planted setup.

What does Quillwort add to a tank with Redtail Splitfin?

Quillwort is less tempting than softer, more palatable plants for known nibblers.

What is the main risk in this plant and fish pairing?

Their hardness ranges are too far apart for a reliable long-term match.