Can Freshwater Toadfish (Prehistoric Monster Fish) and Reedfish (Ropefish) Live Together?

Reviewed by Guidarium Editorial DeskUpdated May 11, 2026
Not Recommended

Freshwater Toadfish (Prehistoric Monster Fish) and Reedfish (Ropefish) are not recommended as tank mates due to slime coat eaters target slow-moving fish, causing severe stress and health issues.. Housing these species together is likely to result in stress, health problems, or direct harm to one or both fish.


At a Glance

Freshwater Toadfish (Prehistoric Monster Fish)

Thalassophryne amazonica

Reedfish (Ropefish)

Erpetoichthys calabaricus

🐟Family Group
Freshwater Toadfish (Prehistoric Monster Fish)
Oddballs
Reedfish (Ropefish)
Oddballs
Temperament
Freshwater Toadfish (Prehistoric Monster Fish)
Aggressive (7/10)
Reedfish (Ropefish)
Mostly Peaceful (3/10)
Temperature
✓ Compatible
Freshwater Toadfish (Prehistoric Monster Fish)
24–28°C
Reedfish (Ropefish)
22–28°C
pH Range
✓ Compatible
Freshwater Toadfish (Prehistoric Monster Fish)
6–7.5
Reedfish (Ropefish)
6–7.5
Hardness (dGH)
✓ Compatible
Freshwater Toadfish (Prehistoric Monster Fish)
4–15
Reedfish (Ropefish)
5–20
Water Type
✓ Compatible
Freshwater Toadfish (Prehistoric Monster Fish)
Freshwater Only
Reedfish (Ropefish)
Freshwater Only
Flow Preference
✓ Compatible
Freshwater Toadfish (Prehistoric Monster Fish)
Low
Reedfish (Ropefish)
Low
Min Tank Volume
Combined: 180 L
Freshwater Toadfish (Prehistoric Monster Fish)
75 L
Reedfish (Ropefish)
180 L
Swimming Level
Shared: 1 zone
Freshwater Toadfish (Prehistoric Monster Fish)
Bottom
Reedfish (Ropefish)
BottomMiddle
🏷️Behavior Tags
Freshwater Toadfish (Prehistoric Monster Fish)
Piscivore (Eats small/nano fish)NocturnalShy / Slow Moving (Easily Stressed)
Reedfish (Ropefish)
Piscivore (Eats small/nano fish)Shrimp EaterJumper (Lid Required)NocturnalHyperactive / Fast SwimmerSlime Coat Eater (Attacks Flat Fish)
Stocking calculator

Can your tank handle Freshwater Toadfish (Prehistoric Monster Fish) and Reedfish (Ropefish)?

Compatibility is only part of the answer. Test both fish with your real tank size, current stock, and maintenance needs to see if you have enough space and a safe stocking level before you add them.

Freshwater Toadfish (Prehistoric Monster Fish)
Reedfish (Ropefish)
Test both in my tank

Behaviour & Temperament

Freshwater Toadfish (Prehistoric Monster Fish) is a semi-aggressive species (7/10), while Reedfish (Ropefish) is generally mild-mannered (3/10). This notable difference means Freshwater Toadfish (Prehistoric Monster Fish) may occasionally assert dominance over Reedfish (Ropefish).

Freshwater Toadfish (Prehistoric Monster Fish) and Reedfish (Ropefish) both frequent the Bottom (Substrate) region of the setup. This overlap can increase competition for space, so providing ample room and cover is important to keep both species comfortable.

There is a critical concern: the Shy / Slow Moving (Easily Stressed) behaviour of one fish directly conflicts with the Slime Coat Eater (Attacks Flat Fish) trait of the other — slime coat eaters target slow-moving fish, causing severe stress and health issues..

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

Worth noting: Freshwater Toadfish (Prehistoric Monster Fish) is nocturnal and will be most active after lights-out, naturally reducing daytime encounters. Also, Reedfish (Ropefish) 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 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.

Tank Setup

To house Freshwater Toadfish (Prehistoric Monster Fish) and Reedfish (Ropefish) together, plan for an aquarium of at least 180 litres with a minimum length of 120 cm. This recommendation combines the stricter species minimums with a community-load allowance so the pairing has realistic long-term space and filtration headroom.

Providing a mix of open swimming space and sheltered areas with rocks, driftwood, or plants will keep both species comfortable and allow natural behaviour.

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

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

Why This Pairing Usually Fails in Practice

Freshwater Toadfish (Prehistoric Monster Fish) and Reedfish (Ropefish) are the kind of pair that can look acceptable in a shop but become a maintenance problem at home. The main risk is not a single number in the chart; it is the way incompatible behavior, water needs, or pressure on space compounds over time once both fish are established in the same tank.

Suitable Tank Sizes

Standard aquarium sizes large enough for both Freshwater Toadfish (Prehistoric Monster Fish) and Reedfish (Ropefish).

Show 5 more tank sizes

Frequently Asked Questions

Can Freshwater Toadfish (Prehistoric Monster Fish) and Reedfish (Ropefish) live together?

No. This combination is not recommended. Key incompatibilities — such as critical behavioural conflicts — make cohabitation unsafe.

What size tank do Freshwater Toadfish (Prehistoric Monster Fish) and Reedfish (Ropefish) need?

A minimum of 180 litres (tank length at least 120 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 Freshwater Toadfish (Prehistoric Monster Fish) and Reedfish (Ropefish) 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 Freshwater Toadfish (Prehistoric Monster Fish) or Reedfish (Ropefish) aggressive?

Freshwater Toadfish (Prehistoric Monster Fish) is semi-aggressive (7/10) and Reedfish (Ropefish) is generally mild-mannered (3/10). The gap in aggression levels means the calmer fish may experience stress from the more assertive one.

What pH do Freshwater Toadfish (Prehistoric Monster Fish) and Reedfish (Ropefish) 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 Freshwater Toadfish (Prehistoric Monster Fish) being nocturnal affect compatibility?

Freshwater Toadfish (Prehistoric Monster Fish) 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 Freshwater Toadfish (Prehistoric Monster Fish) during evening hours.

Editorial Review

Guidarium Editorial Desk

Reviewed against Guidarium care, stocking, and compatibility standards. Read the editorial policy.

Last reviewed
May 11, 2026
Last updated
May 11, 2026
Issues or corrections?
Contact the editorial team

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