Can Molly (Sailfin/Black/Dalmatian) and Tire Track Eel Live Together?

🟡Possible with Caution

Keeping Molly (Sailfin/Black/Dalmatian) and Tire Track Eel together is possible but requires caution, though some care is needed. Provide a spacious tank of at least 816 litres with plenty of hiding spots to reduce stress. Monitor behaviour closely, especially during the first few weeks.


At a Glance

Molly (Sailfin/Black/Dalmatian)

Poecilia sphenops

Tire Track Eel

Mastacembelus armatus

🐠Family Group
Molly (Sailfin/Black/Dalmatian)
Livebearers
Tire Track Eel
Oddballs
Temperament
Molly (Sailfin/Black/Dalmatian)
Mostly Peaceful (3/10)
Tire Track Eel
Semi-Aggressive (6/10)
Temperature
✓ Compatible
Molly (Sailfin/Black/Dalmatian)
24–28°C
Tire Track Eel
22–28°C
pH Range
✓ Compatible
Molly (Sailfin/Black/Dalmatian)
7.5–8.5
Tire Track Eel
6.5–7.5
Hardness (dGH)
✓ Compatible
Molly (Sailfin/Black/Dalmatian)
12–30
Tire Track Eel
5–15
Water Type
✓ Compatible
Molly (Sailfin/Black/Dalmatian)
Brackish Tolerant
Tire Track Eel
Freshwater Only
Flow Preference
✓ Compatible
Molly (Sailfin/Black/Dalmatian)
Moderate
Tire Track Eel
Moderate
Min Tank Volume
Combined: 816 L
Molly (Sailfin/Black/Dalmatian)
75 L
Tire Track Eel
680 L
Swimming Level
✓ Different zones
Molly (Sailfin/Black/Dalmatian)
TopMiddle
Tire Track Eel
Bottom
🏷️Behavior Tags
Molly (Sailfin/Black/Dalmatian)
Hyperactive / Fast SwimmerFry PredatorAggressive Eater (Starves shy fish)
Tire Track Eel
Piscivore (Eats small/nano fish)Shrimp EaterDigger (Disturbs Substrate)Jumper (Lid Required)NocturnalAggressive to same species/look-alikes

Behaviour & Temperament

Molly (Sailfin/Black/Dalmatian) is a generally mild-mannered species (3/10), while Tire Track Eel is moderately assertive (6/10). This modest difference means Tire Track Eel may occasionally assert dominance over Molly (Sailfin/Black/Dalmatian).

In terms of spatial distribution, Molly (Sailfin/Black/Dalmatian) prefers the Top (Surface) and Middle (Open Water) zones, whereas Tire Track Eel occupies the Bottom (Substrate) zone. Because they use different levels of the water column, territorial disputes are less likely and the tank will appear more balanced.

Worth noting: Tire Track Eel is nocturnal and will be most active after lights-out, naturally reducing daytime encounters. Also, Tire Track Eel is a known jumper, so a tight-fitting lid is essential.

Water Parameters

The safe temperature window for both species falls between 24°C and 28°C. Aim for the midpoint of this range (around 26.0°C) for optimal comfort.

Both fish can tolerate a pH between 7.5 and 7.5. Maintaining a stable value within this band is more important than hitting an exact number.

For general hardness, the shared comfort zone is 12–15 dGH. Regular testing will ensure conditions stay within this range. An aquarium test kit is recommended for monitoring.

Tank Setup

To house Molly (Sailfin/Black/Dalmatian) and Tire Track Eel together, plan for an aquarium of at least 816 litres with a minimum length of 180 cm. This accounts for the larger species' space requirements with an additional 20 % buffer to reduce territorial tension.

Because this pairing requires extra vigilance, include plenty of hiding spots — caves, driftwood, and dense plant clusters — so the less dominant fish can retreat when needed.

Specific environmental needs for this combination include: Plants - Densely covered, Established Algae (Otocinclus), Sand (Sifters), Smooth Gravel (Sensitive Barbels), Driftwood (Digestion/Hiding). Meeting these requirements will help both species thrive.

Both species do well with moderate (standard) water movement, so a standard filtration setup rated for the tank volume should suffice.

Find the right tank equipment

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Frequently Asked Questions

Can Molly (Sailfin/Black/Dalmatian) and Tire Track Eel live together?

They can coexist, but the pairing requires careful monitoring. Provide ample space (at least 816 litres), plenty of hiding spots, and watch for signs of stress or aggression.

What size tank do Molly (Sailfin/Black/Dalmatian) and Tire Track Eel need?

A minimum of 816 litres (tank length at least 180 cm) is recommended. This provides enough space for both species to establish their own areas and reduces the likelihood of territorial disputes.

What water temperature is best for Molly (Sailfin/Black/Dalmatian) and Tire Track Eel together?

Keep the aquarium between 24°C and 28°C. A target of around 26.0°C sits comfortably within both species' preferred ranges.

Are Molly (Sailfin/Black/Dalmatian) or Tire Track Eel aggressive?

Molly (Sailfin/Black/Dalmatian) is generally mild-mannered (3/10) and Tire Track Eel is moderately assertive (6/10). Their similar temperaments generally lead to a peaceful coexistence.

What pH do Molly (Sailfin/Black/Dalmatian) and Tire Track Eel need?

Both species overlap in the 7.5–7.5 pH range. Consistency is key — avoid sudden swings, and test regularly to stay within this window.

Does Tire Track Eel being nocturnal affect compatibility?

Tire Track Eel is most active after lights-out, which naturally reduces daytime encounters with its tank mate. This can actually be beneficial, as both fish get undisturbed time to feed and explore. Just ensure food reaches Tire Track Eel during evening hours.


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