Can Common Pleco and Japanese Ricefish (Medaka) Live Together?

🟢Ideal Tank Mates

Yes, Common Pleco and Japanese Ricefish (Medaka) are ideal tank mates. Both species share compatible water parameters and peaceful temperaments, making them well-suited for a community aquarium. They occupy different areas of the water column, which reduces competition for space. A minimum tank size of 600 litres is recommended.


At a Glance

Common Pleco

Hypostomus plecostomus

Japanese Ricefish (Medaka)

Oryzias latipes

🐠Family Group
Common Pleco
Catfish
Japanese Ricefish (Medaka)
Killifish
Temperament
Common Pleco
Mostly Peaceful (4/10)
Japanese Ricefish (Medaka)
Peaceful (2/10)
Temperature
✓ Compatible
Common Pleco
20–28°C
Japanese Ricefish (Medaka)
10–28°C
pH Range
✓ Compatible
Common Pleco
6–8
Japanese Ricefish (Medaka)
6.5–8.5
Hardness (dGH)
✓ Compatible
Common Pleco
4–15
Japanese Ricefish (Medaka)
5–25
Water Type
✓ Compatible
Common Pleco
Freshwater Only
Japanese Ricefish (Medaka)
Brackish Tolerant
Flow Preference
✓ Compatible
Common Pleco
Moderate
Japanese Ricefish (Medaka)
Low
Min Tank Volume
Combined: 600 L
Common Pleco
500 L
Japanese Ricefish (Medaka)
19 L
Swimming Level
✓ Different zones
Common Pleco
Bottom
Japanese Ricefish (Medaka)
Top
🏷️Behavior Tags
Common Pleco
NocturnalPlant DestroyerSlime Coat Eater (Attacks Flat Fish)Territorial (Defends specific area)
Japanese Ricefish (Medaka)
Nano / Bite-sized (Predation Risk)Hyperactive / Fast SwimmerJumper (Lid Required)Fry Predator

Behaviour & Temperament

Common Pleco is a generally mild-mannered species (4/10), while Japanese Ricefish (Medaka) is peaceful (2/10). This modest difference means Common Pleco may occasionally assert dominance over Japanese Ricefish (Medaka).

In terms of spatial distribution, Common Pleco prefers the Bottom (Substrate) zone, whereas Japanese Ricefish (Medaka) occupies the Top (Surface) zone. Because they use different levels of the water column, territorial disputes are less likely and the tank will appear more balanced.

Worth noting: Common Pleco is nocturnal and will be most active after lights-out, naturally reducing daytime encounters. Also, Japanese Ricefish (Medaka) is a known jumper, so a tight-fitting lid is essential.

Water Parameters

The safe temperature window for both species falls between 20°C and 28°C. Aim for the midpoint of this range (around 24.0°C) for optimal comfort.

Both fish can tolerate a pH between 6.5 and 8. 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 Common Pleco and Japanese Ricefish (Medaka) together, plan for an aquarium of at least 600 litres with a minimum length of 150 cm. This accounts for the larger species' space requirements with an additional 20 % buffer to reduce territorial tension.

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: Driftwood (Digestion/Hiding), Smooth Gravel (Sensitive Barbels), Plants - Densely covered, Plants - Floating. Meeting these requirements will help both species thrive.

Note a potential conflict in setup requirements: Common Pleco is a plant destroyer, which conflicts with Japanese Ricefish (Medaka)'s requirement for live plants. Compromise where possible or prioritise the more critical need.

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

Browse tanks, décor, and equipment suited for this setup.

Frequently Asked Questions

Can Common Pleco and Japanese Ricefish (Medaka) live together?

Yes. Common Pleco and Japanese Ricefish (Medaka) are considered ideal tank mates. Their water parameters, temperaments, and behaviour profiles are well matched for a community aquarium.

What size tank do Common Pleco and Japanese Ricefish (Medaka) need?

A minimum of 600 litres (tank length at least 150 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 Common Pleco and Japanese Ricefish (Medaka) together?

Keep the aquarium between 20°C and 28°C. A target of around 24.0°C sits comfortably within both species' preferred ranges.

Are Common Pleco or Japanese Ricefish (Medaka) aggressive?

Common Pleco is generally mild-mannered (4/10) and Japanese Ricefish (Medaka) is peaceful (2/10). Their similar temperaments generally lead to a peaceful coexistence.

What pH do Common Pleco and Japanese Ricefish (Medaka) need?

Both species overlap in the 6.5–8 pH range. Consistency is key — avoid sudden swings, and test regularly to stay within this window.

How do I manage Common Pleco's territorial behaviour?

Provide line-of-sight breaks using rocks, driftwood, and dense planting. A larger tank gives Common Pleco space to claim a territory without encroaching on the other fish's area. Adding décor that divides the tank into distinct zones works especially well.

Does Common Pleco being nocturnal affect compatibility?

Common Pleco 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 Common Pleco during evening hours.


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