Killifish: gear and buying guides
Killifish, such as Aphyosemion australe, are small, brilliantly colored fish often content with 20 to 50 L tanks. Many prefer soft, slightly acidic and rather cool water, between 20 and 24 °C, with subdued lighting. Outstanding jumpers, they demand a lid with no gaps at all; some annual species have naturally short lifespans.
Profile : 4 to 6 cm as an adult depending on the species, 20 to 50 L depending on the species, water between 20 and 24 °C.
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Species profile
- Lifespan
- 1 to 3 years
- Adult size
- 5 cm
- Minimum tank
- 20 L
- Water temperature
- 20 to 24 °C
- pH
- 6 to 7
- Temperament
- A lively, colorful little surface fish, often kept species-only with one male and two or three females.
- Health watch
- velvet (oodinium) in unstable water · sensitivity to elevated nitrates
🩺 Our hygiene and health advice stays general: it never substitutes for an examination by a veterinarian, the only person qualified to advise on your animal.
Killifish gear, family by family
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Food
A surface carnivore that prefers live and frozen foods: brine shrimp, daphnia, grindal worms. Many killifish snub dry flakes, so keep a stock of frozen food.
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Care & grooming
Soft, slightly acidic water without elevated nitrates, often softened with RO water. Constantly warm temperatures noticeably shorten its lifespan.
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Toys & enrichment
Floating plants, Java moss and a dark substrate show off its colors and reassure it. A synthetic-yarn spawning mop encourages breeding behavior.
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Bedding & habitat
A 20 to 50 L tank depending on the species, gently filtered, often kept species-only with one male and two or three females. A gap-free lid is the number one safety point.
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Travel & safety
It jumps the moment the bag opens: handle it above a closed surface and transfer carefully. Slow 30 to 45 minute acclimation, especially into harder water.
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Accessories
A sponge filter, a snug lid, peat or catappa leaves for acidifying and a spawning mop. A small budget of around 60 to 120 euros for a complete species tank.
🧴 Water care for a Killifish: 20 to 24°C, pH 6 to 7
The Killifish’s water: its real parameters
For a Killifish, water quality comes in numbers: 20 to 24°C on the thermometer, pH within the 6 to 7 window, nitrites at zero, nitrates under the 25 mg/L bar. A drop-test kit (NO2, NO3, GH, KH, pH) beats any strip — and the nitrogen cycle, three to four weeks before any fish, is non-negotiable.
Water changes and tank upkeep
10 to 20% of the volume weekly, with water pre-heated to tank temperature: thermal shock stresses more than imperfect water, gentle substrate siphoning as you go and filter media rinsed in tank water, never under the tap: chlorine sterilises your filter.
Health: what stalks the Killifish
In the Killifish, watch for: velvet (oodinium) in unstable water and sensitivity to elevated nitrates. But the golden rule holds for the whole tank — nearly all disease starts in degraded water or chronic stress, and you ALWAYS test the water before reaching for medicine. Well kept, a Killifish lives 1 to 3 years.
Quick answers
- What water parameters for a Killifish?
- 20 to 24°C, pH 6 to 7, zero nitrites and nitrates under 25 mg/L — checked with drop tests, not by eye.
- How often should a Killifish tank get water changes?
- 10 to 20% weekly, water brought to temperature, filter rinsed only in tank water. Consistency beats volume.
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🧳 Transporting a Killifish: bagging, acclimatisation, moving
Bringing home or moving a Killifish
A 5 cm Killifish travels in a double bag — one-third water, two-thirds air — inside a cool box or opaque bag: darkness soothes, insulation protects from swings away from its 20 to 24°C comfort zone. A trip under two hours needs nothing more.
Acclimatisation: the critical step
On arrival, float the bag 20 minutes to equalise temperature, then add tank water in small doses over 30 to 45 minutes, and release with a net without pouring bag water into the tank. In this species, a botched transfer is paid for in bouts of velvet (oodinium) in unstable water. Lights off for the first day: a newcomer hazed under floodlights starts with a handicap.
Moving an entire aquarium
A successful move rests on three precautions: fish in covered buckets, the filter never dried out (damp cool box — it houses your bacteria), and a same-day restart using original water saved in jerrycans. The tank itself travels EMPTY: glass stressed by a few leftover litres cracks at the first corner.
Quick answers
- How long can a Killifish handle transport?
- A few hours easily in a proper bag, up to 24 hours in an oxygenated professional bag. Past two hours, protect the temperature above all.
- How do you acclimatise a Killifish safely?
- Float the bag 20 minutes, add tank water gradually over 30 to 60 minutes, release with a net, lights off the first day — and never pour bag water into the tank.
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🧰 Accessories for a Killifish: tests, upkeep and budget
Water tests: your dashboard
Before any decor, equip the Killifish tank with a drop-test kit (€15-30): nitrites and nitrates weekly, hardness and pH whenever doubt creeps in. Then come the net sized for 5 cm, the substrate siphon and the dedicated bucket — never the cleaning one, whose detergent traces contaminate the water.
The Killifish specifics
a tight-fitting lid with no gaps: the species jumps, and every slot is a one-way exit.
The full budget, no surprises
An equipped 20 L setup (tank, filter, heater, lighting, substrate, decor, tests): expect €100 to 250 upfront, then €10 to 25 a month (food, electricity, conditioner). Second-hand often halves the tank price — only the filter and heater deserve to be new. Details on the full Killifish profile.
Quick answers
- Which accessories are essential for a Killifish tank?
- Drop tests, siphon, net, dedicated bucket, a tight lid (it jumps), an independent thermometer: the whole kit stays under €60.
- What budget for keeping a Killifish?
- €100 to 250 to set up an equipped 20 L tank, then €10 to 25 a month in routine costs.
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Guides to read
- Community aquarium or species-only tank: which is right for a first setup?Bedding & habitat
Community aquarium or species-only tank: pros, cohabitation risks and advice for choosing how to set up your first aquarium.
- Best easy aquarium plants without CO2 for beginnersToys & enrichment
Which aquarium plants can you choose without CO2 injection? A selection of hardy, easy plants for a beginner's planted tank.
- Budget for a first brackish water aquarium: the real cost to get startedBedding & habitat
How much does a first brackish water aquarium cost? Tank, filtration, salt and salinity monitoring, budgeted item by item.
- Changing filter media too often: the mistake that wrecks your aquarium's cycleCare & grooming
Why you should never replace all your filter media at once: nitrifying bacteria, replacement frequency and the right habits.
- Restarting a neglected aquarium: a step-by-step guideCare & grooming
How do you restart an aquarium that's been left neglected without endangering the fish? Steps, water changes and mistakes to avoid.
- GH, KH and pH: understanding and adjusting aquarium water hardnessCare & grooming
GH, KH, pH: what do these three readings actually measure, and how do you adjust aquarium water hardness without stressing the fish?
- Upgrading to a bigger aquarium: moving your fish without the stressBedding & habitat
How do you upgrade to a bigger aquarium without breaking the biological cycle or stressing your fish? Steps and mistakes to avoid.
- Aquarium electrical safety: GFCI protection and good habitsTravel & safety
Heater, filter, lighting near the water: what electrical precautions keep an aquarium safe for fish and people?