Can Common Pleco and Rachov's Killifish (Annual) Live Together?

🟢Ideal Tank Mates

Yes, Common Pleco and Rachov's Killifish (Annual) are ideal tank mates. Both species share compatible water parameters and peaceful temperaments, making them well-suited for a community aquarium. A minimum tank size of 600 litres is recommended.


At a Glance

Common Pleco

Hypostomus plecostomus

Rachov's Killifish (Annual)

Nothobranchius rachovii

🐠Family Group
Common Pleco
Catfish
Rachov's Killifish (Annual)
Killifish
Temperament
Common Pleco
Mostly Peaceful (4/10)
Rachov's Killifish (Annual)
Mostly Peaceful (3/10)
Temperature
✓ Compatible
Common Pleco
20–28°C
Rachov's Killifish (Annual)
20–26°C
pH Range
✓ Compatible
Common Pleco
6–8
Rachov's Killifish (Annual)
6–7.5
Hardness (dGH)
✓ Compatible
Common Pleco
4–15
Rachov's Killifish (Annual)
4–12
Water Type
✓ Compatible
Common Pleco
Freshwater Only
Rachov's Killifish (Annual)
Freshwater Only
Flow Preference
✓ Compatible
Common Pleco
Moderate
Rachov's Killifish (Annual)
Low
Min Tank Volume
Combined: 600 L
Common Pleco
500 L
Rachov's Killifish (Annual)
19 L
Swimming Level
Shared: 1 zone
Common Pleco
Bottom
Rachov's Killifish (Annual)
MiddleBottom
🏷️Behavior Tags
Common Pleco
NocturnalPlant DestroyerSlime Coat Eater (Attacks Flat Fish)Territorial (Defends specific area)
Rachov's Killifish (Annual)
Nano / Bite-sized (Predation Risk)Hyperactive / Fast SwimmerJumper (Lid Required)

Behaviour & Temperament

Common Pleco is a generally mild-mannered species (4/10), while Rachov's Killifish (Annual) is generally mild-mannered (3/10). This modest difference means Common Pleco may occasionally assert dominance over Rachov's Killifish (Annual).

Common Pleco and Rachov's Killifish (Annual) 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.

Worth noting: Common Pleco is nocturnal and will be most active after lights-out, naturally reducing daytime encounters. Also, Rachov's Killifish (Annual) 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 26°C. Aim for the midpoint of this range (around 23.0°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 4–12 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 Rachov's Killifish (Annual) 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), Soil / Nutrient Rich, Leaf Litter/Blackwater, Plants - Densely covered. Meeting these requirements will help both species thrive.

Note a potential conflict in setup requirements: Common Pleco requires Smooth Gravel (Sensitive Barbels), while Rachov's Killifish (Annual) requires Soil / Nutrient Rich. These substrate types may be difficult to provide simultaneously. Common Pleco is a plant destroyer, which conflicts with Rachov's Killifish (Annual)'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 Rachov's Killifish (Annual) live together?

Yes. Common Pleco and Rachov's Killifish (Annual) 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 Rachov's Killifish (Annual) 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 Rachov's Killifish (Annual) together?

Keep the aquarium between 20°C and 26°C. A target of around 23.0°C sits comfortably within both species' preferred ranges.

Are Common Pleco or Rachov's Killifish (Annual) aggressive?

Common Pleco is generally mild-mannered (4/10) and Rachov's Killifish (Annual) is generally mild-mannered (3/10). Their similar temperaments generally lead to a peaceful coexistence.

What pH do Common Pleco and Rachov's Killifish (Annual) 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.

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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