Steel-blue Killifish

About

Buy a killifish and the first thing worth knowing is whether it is supposed to die inside a year. For this one the answer is no. FishBase states it flatly - "Not a seasonal killifish" - so there is no built-in one-season clock, and a fish that dies at ten months died of something you can find. That agrees with our lyretail killifish (Aphyosemion australe), which is non-annual on the same authorities. Note that neither species' Wikipedia article makes any annual/non-annual statement at all, so do not take one from there. What Wikipedia does describe - and Seriously Fish says it in almost the same words - is the thing that gets misread as annual: "It has evolved a spawning strategy which is frequently referred to as a 'switch' or 'semi-annual' breeding strategy. This means that the eggs can survive a period of drying but that they are also viable when permanently submerged." That is a property of the eggs, not a sentence passed on the fish. Breeders use it by storing eggs three to four weeks in damp peat; left in water the same eggs hatch in 14-21 days. The fish itself is a 6.5 cm West African rivuline from the tributary streams and marshes of the Cross and Benue basins in Nigeria and Cameroon, described by Boulenger in 1911 from Okwoga in the headwaters of the Cross River and named for a Captain R. D. Gardner, who collected the type. Males are the electric blue ones, marked with wavy rows of red spots and yellow-edged fins; females are smaller, brown-spotted and plain. Wild populations come in many colour forms, three of which - lacustris, mamfensis and nigerianus - carry subspecies names, and aquarium strains include line-bred gold and albino forms. Shop stock therefore often arrives under a locality code rather than a plain species name, and mixing codes ends a line somebody spent years keeping separate.

Care

One male to two or three females in a densely planted tank of its own. Seriously Fish is direct about the company: "This is a robust killi that can be kept with other fishes but is not suitable for the general community", and Maidenhead Aquatics reaches the same verdict, naming West African dwarf cichlids as the exception in a large enough tank. Males fight one another, so a group needs refuges and broken sight lines rather than open water - Seriously Fish notes that "provided the aquarium contains sufficient refuges a group can normally be maintained together". The lid is not optional: Seriously Fish calls it "a prodigious jumper" and Maidenhead says "tight fitting coverslides are a must as these fish are expert jumpers". Soft to medium water, pH 6.0-7.2, 23-25 C; FishBase and Maidenhead both quote 22-25 C, so the cooler end is normal rather than a compromise. Sixty centimetres of base is enough, which is the minimum aquarium size FishBase gives. Seriously Fish rates the ordinary trade forms as "perhaps among the best choices for those new to keeping killifishes being relatively hardy, colourful and easy to breed".

Diet

Micropredator on small crustaceans, worms, insect larvae and zooplankton. Live and frozen daphnia, mosquito larvae, bloodworm, cyclops and Artemia; tank-bred fish also take flake and granules, but check that they are actually eating.

Telling males from females

What works for this species, most reliable first.

• Colour and patternStrong · from about 6 months, and only on a settled fish

  In rainbowfish, killifish and several barbs the male carries the colour — deeper and more saturated, intensifying further when he displays.

• Extended finsStrong · from about 8 months, and later in a suppressed male

  On many cichlids and killifish the male's dorsal and anal fins draw out into trailing points as he matures, while the female's stay rounded.

Also in these lists

Similar species

Same category and the closest water parameters — if this species isn't quite it, start here.

Sold in Lithuania

These Lithuanian shops listed this species in their public catalogue (checked August 8, 2026). Stock moves — ask before you travel.

These links are unpaid: we get nothing for them and ask for nothing.

Frequently asked questions

What tank size does a Steel-blue Killifish need?

A Steel-blue Killifish needs an aquarium of at least 60 litres (15.9 US gallons) with a footprint at least 60 cm (23.6 in) long — for this species, swimming length matters as much as raw volume.

What water parameters does a Steel-blue Killifish need?

Steel-blue Killifish does best at 20–26 °C (68–78.8 °F), pH 6–7.5 and a general hardness of 1–12 °dGH.

Is the Steel-blue Killifish suitable for beginners?

Yes — Steel-blue Killifish is one of the easier species to keep and forgives typical first-tank mistakes, as long as the aquarium is cycled and maintained.

Sources

• Seriously Fish — Fundulopanchax gardneri (Steel-blue Killifish)
• FishBase — Fundulopanchax gardneri (Boulenger, 1911), Blue lyretail
• Wikipedia — Blue lyretail (Fundulopanchax gardneri)
• Maidenhead Aquatics — Steel Blue Killifish (Fundulopanchax gardneri)
• Aquadiction — Steel Blue Lyretail Killifish (Fundulopanchax gardneri)