Care guide · Freshwater · fish

Bluefin notho

Nothobranchius rachovii

Young male Nothobranchius rachovii. Photo: Violaine2, CC BY-SA 3.0. Photo: Violaine2 / Wikimedia Commons · Source · CC BY-SA 3.0; GFDL 1.2 or laterProportional resize only; no crop or colour edit. Attribution and CC BY-SA 3.0/GFDL 1.2+ terms retained.

The bluefin notho (Nothobranchius rachovii) is a striking African killifish from temporary waters in eastern Mozambique. Males show vivid blue and orange-red markings; females are smaller and far less conspicuous. In nature the fish inhabit pools formed in the rainy season that later dry out. Adults therefore live briefly, while eggs survive a dry period in the substrate and hatch later. This makes the species fascinating for experienced keepers, but a poor impulse choice for a community aquarium. A stable, covered species tank, suitably small animal foods and advance planning for breeding are important. Prefer a traceable captive line and keep locality codes separate.

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At a glance

Temperature: 20–24 °C
pH: 6.0–7.5
GH: 3–10 °dGH
Aquarium length: At least 45 cm
Minimum aquarium volume: At least 41 L
Adult size: Up to 6 cm
Group size: At least 2 individuals
Swimming zone: Middle
Temperament: Territorial

About this species

GBIF, FishBase and the taxonomic revision by Shidlovskiy, Watters and Wildekamp accept Nothobranchius rachovii Ahl, 1926, in Nothobranchiidae. Its current species range is narrower than older aquarium accounts suggested: northern and southern populations have been described as N. krysanovi and N. pienaari. A trade name or colour pattern alone does not prove provenance. FishBase reports a maximum total length of 6 cm; Seriously Fish gives about 55 mm standard length. These are different measurements. Males are larger and more colourful; females are generally smaller and silvery grey with reflective flank spots.

Natural habitat

Nothobranchius rachovii sensu stricto occurs on lowland floodplains between the lower Pungwe and Zambezi rivers in Mozambique. It inhabits temporary pools, swamps and water-filled depressions. During the dry season these waters recede and eventually dry for months. Adults die as their habitat disappears, while resistant eggs remain in the substrate. When rains return, fry hatch and grow rapidly. Local pools have marginal grasses and aquatic plants such as Nymphaea, Ottelia, Lagarosiphon and Utricularia. Reported habitat pH is context, not a universal aquarium recipe. Recreate calm water, cover and careful husbandry; never let a home aquarium dry out.

Aquarium and layout

Seriously Fish gives a minimum base of 45 × 30 cm and approximately 41 litres; volume depends on water depth. Treat this as a specialist profile’s lower reference, not a reason to overstock. Keep the fish in a species tank or a carefully planned setup with adequate floor space. A sponge filter or other gentle biological filtration avoids strong flow and reduces the chance of eggs or fry being drawn in. Use subdued, dark decor and plants as visual barriers; a suitable spawning medium can be offered separately. A tight lid is sensible. Choose tank mates only after checking adult size, behaviour and food competition; for many keepers a species tank is safest.

Water conditions

FishBase reports natural-water values of 20–24°C, pH 6–7 and GH 4–6 °dH. Seriously Fish gives the same aquarium temperature range, with pH 6.0–7.5 and GH 3–10 dGH. A stable overlap in soft to moderately hard water is practical; avoid rapid swings and do not chase a pH number. Test source water and acclimate gradually. This short life cycle makes stable temperature and water quality especially important: stress or poor water quickly erodes an already limited adult phase. Do not add salt, peat extract or buffers without a clear reason and monitoring plan.

Behaviour and group size

This is not a typical shoaling community fish. Seriously Fish lists pair keeping as a social guide and advises choosing conspecifics and tank mates carefully. Males are more colourful and may chase one another or females; visual barriers and sufficient space help, but observation is still necessary. Smaller animals and fry may be eaten, and adults consume eggs or newly hatched fry. Do not plant the entire water column so densely that feeding and observation become difficult. Watch for damaged fins, persistent chasing and fish unable to reach food. If preserving a particular locality line matters, do not mix line codes.

Feeding

Nothobranchius rachovii is a small predator that feeds mainly on small invertebrates. Seriously Fish lists small live or frozen prey such as Daphnia, Artemia and finely chopped bloodworms as the dietary basis. Offer portions that are eaten promptly and rotate prey types. Dry food is not guaranteed to be accepted; use it only as a supplement and in a suitable size when you have observed the fish eating it. Newly hatched fry need extremely small first foods. Remove leftovers promptly to protect water quality in a relatively small aquarium.

Breeding

This is an annual killifish. Eggs are deposited in fine substrate or a dedicated spawning medium and tolerate drying. In nature development resumes when water returns; captive breeding uses a moist incubation period followed by controlled rewetting. Seriously Fish gives about five to seven months of egg storage at roughly 21–25°C and an adult lifespan of about six to twelve months; treat these as specialist references, not guarantees for every line. Adults eat eggs and fry, so remove spawning material in time if raising young. Record dates, line codes and conditions. Prepare tiny first foods, a separate grow-out space and a responsible plan for offspring in advance.

Sources & review

This care guide draws on several specialist sources and was last checked on 17 October 2026.

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