Can Fire Eel and Silver Dollar Live Together?

🟡Possible with Caution

Keeping Fire Eel and Silver Dollar together is possible but requires caution due to potential behavioral clashes. 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

Fire Eel

Mastacembelus erythrotaenia

Silver Dollar

Metynnis argenteus

🐠Family Group
Fire Eel
Oddballs
Silver Dollar
Characins
Temperament
Fire Eel
Mostly Peaceful (4/10)
Silver Dollar
Peaceful (2/10)
Temperature
✓ Compatible
Fire Eel
24–28°C
Silver Dollar
24–28°C
pH Range
✓ Compatible
Fire Eel
6–7.5
Silver Dollar
5.5–7.5
Hardness (dGH)
✓ Compatible
Fire Eel
5–15
Silver Dollar
4–15
Water Type
✓ Compatible
Fire Eel
Freshwater Only
Silver Dollar
Freshwater Only
Flow Preference
✓ Compatible
Fire Eel
Moderate
Silver Dollar
Moderate
Min Tank Volume
Combined: 816 L
Fire Eel
680 L
Silver Dollar
280 L
Swimming Level
✓ Different zones
Fire Eel
Bottom
Silver Dollar
MiddleTop
🏷️Behavior Tags
Fire Eel
Piscivore (Eats small/nano fish)Shrimp EaterDigger (Disturbs Substrate)Jumper (Lid Required)NocturnalShy / Slow Moving (Easily Stressed)
Silver Dollar
Plant DestroyerHyperactive / Fast SwimmerShy / Slow Moving (Easily Stressed)Jumper (Lid Required)

Behaviour & Temperament

Fire Eel is a generally mild-mannered species (4/10), while Silver Dollar is peaceful (2/10). This modest difference means Fire Eel may occasionally assert dominance over Silver Dollar.

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

Additional behavioural considerations to keep in mind: Hyperactive swimmers can stress shy, slow-moving species through constant motion.

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

To improve the chances of a peaceful coexistence in this community tank: A larger aquarium with ample hiding spots can help diffuse aggression and give the less dominant fish space to retreat.

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 6 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 5–15 dGH. Regular testing will ensure conditions stay within this range. An aquarium test kit is recommended for monitoring.

Tank Setup

To house Fire Eel and Silver Dollar 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: 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 Fire Eel and Silver Dollar 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 Fire Eel and Silver Dollar 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 Fire Eel and Silver Dollar 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 Fire Eel or Silver Dollar aggressive?

Fire Eel is generally mild-mannered (4/10) and Silver Dollar is peaceful (2/10). Their similar temperaments generally lead to a peaceful coexistence.

What pH do Fire Eel and Silver Dollar need?

Both species overlap in the 6–7.5 pH range. Consistency is key — avoid sudden swings, and test regularly to stay within this window.

Does Fire Eel being nocturnal affect compatibility?

Fire 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 Fire Eel during evening hours.


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