Can Bucktooth Tetra (Exodon) and Rachov's Killifish (Annual) Live Together?

🔴Not Recommended

Bucktooth Tetra (Exodon) and Rachov's Killifish (Annual) are not recommended as tank mates due to piscivorous fish will prey on nano-sized tank mates.. Housing these species together is likely to result in stress, health problems, or direct harm to one or both fish.


At a Glance

Bucktooth Tetra (Exodon)

Exodon paradoxus

Rachov's Killifish (Annual)

Nothobranchius rachovii

🐠Family Group
Bucktooth Tetra (Exodon)
Characins
Rachov's Killifish (Annual)
Killifish
Temperament
Bucktooth Tetra (Exodon)
Highly Aggressive (9/10)
Rachov's Killifish (Annual)
Mostly Peaceful (3/10)
Temperature
✓ Compatible
Bucktooth Tetra (Exodon)
23–28°C
Rachov's Killifish (Annual)
20–26°C
pH Range
✓ Compatible
Bucktooth Tetra (Exodon)
5.5–7.5
Rachov's Killifish (Annual)
6–7.5
Hardness (dGH)
✓ Compatible
Bucktooth Tetra (Exodon)
1–15
Rachov's Killifish (Annual)
4–12
Water Type
✓ Compatible
Bucktooth Tetra (Exodon)
Freshwater Only
Rachov's Killifish (Annual)
Freshwater Only
Flow Preference
✓ Compatible
Bucktooth Tetra (Exodon)
Moderate
Rachov's Killifish (Annual)
Low
Min Tank Volume
Combined: 240 L
Bucktooth Tetra (Exodon)
200 L
Rachov's Killifish (Annual)
19 L
Swimming Level
Shared: 1 zone
Bucktooth Tetra (Exodon)
MiddleTop
Rachov's Killifish (Annual)
MiddleBottom
🏷️Behavior Tags
Bucktooth Tetra (Exodon)
Generally AggressiveAggressive to same species/look-alikesFin NipperPiscivore (Eats small/nano fish)Hyperactive / Fast SwimmerEye Biter (Attacks slow moving fish)Jumper (Lid Required)
Rachov's Killifish (Annual)
Nano / Bite-sized (Predation Risk)Hyperactive / Fast SwimmerJumper (Lid Required)

Behaviour & Temperament

Bucktooth Tetra (Exodon) is a highly aggressive species (9/10), while Rachov's Killifish (Annual) is generally mild-mannered (3/10). This notable difference means Bucktooth Tetra (Exodon) may occasionally assert dominance over Rachov's Killifish (Annual).

Large aggression gap (6 points) between Bucktooth Tetra (Exodon) and Rachov's Killifish (Annual) increases stress risk for the more peaceful fish.

Bucktooth Tetra (Exodon) and Rachov's Killifish (Annual) both frequent the Middle (Open Water) 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 Piscivore (Eats small/nano fish) behaviour of one fish directly conflicts with the Nano / Bite-sized (Predation Risk) trait of the other — piscivorous fish will prey on nano-sized tank mates..

Worth noting: Bucktooth Tetra (Exodon) is a known jumper, so a tight-fitting lid is essential.

Water Parameters

The safe temperature window for both species falls between 23°C and 26°C. Aim for the midpoint of this range (around 24.5°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.

Tank Setup

To house Bucktooth Tetra (Exodon) and Rachov's Killifish (Annual) together, plan for an aquarium of at least 240 litres with a minimum length of 120 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), Soil / Nutrient Rich, Leaf Litter/Blackwater, Plants - Densely covered. 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.

Frequently Asked Questions

Can Bucktooth Tetra (Exodon) and Rachov's Killifish (Annual) live together?

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

What size tank do Bucktooth Tetra (Exodon) and Rachov's Killifish (Annual) need?

A minimum of 240 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 Bucktooth Tetra (Exodon) and Rachov's Killifish (Annual) together?

Keep the aquarium between 23°C and 26°C. A target of around 24.5°C sits comfortably within both species' preferred ranges.

Are Bucktooth Tetra (Exodon) or Rachov's Killifish (Annual) aggressive?

Bucktooth Tetra (Exodon) is highly aggressive (9/10) and Rachov's Killifish (Annual) 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 Bucktooth Tetra (Exodon) 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.

Will Bucktooth Tetra (Exodon) nip Rachov's Killifish (Annual)'s fins?

Bucktooth Tetra (Exodon) is a known fin nipper. If Rachov's Killifish (Annual) has long or flowing fins, there is a real risk of fin damage. Keeping Bucktooth Tetra (Exodon) in a larger group can help redirect nipping behaviour toward conspecifics.


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