Yellow-Green Gabon Killie (Aphyosemion gabunense)

Species Overview

Yellow-Green Gabon Killie is a small, colourful rainforest killifish from Gabon, best listed as Aphyosemion gabunense. The supplier name Yellow-Green Killie, Gabon is retained naturally here because it is useful for identifying the exact stock, but the page no longer repeats buyer phrases just to chase search terms.

This listing is for young fish supplied at approximately 3-4 cm. Plan for an adult fish around 5 cm, not a permanently tiny 4 cm nano fish: FishBase and specialist killifish references list males to about 5 cm total length. It is a modest-sized species, but it still deserves stable water, a covered aquarium and calm tank mates.

Name, Range and Habitat

FishBase records Aphyosemion gabunense from Africa, including the lower Ogowe and lower Ngounie river systems. The American Killifish Association/WAK reference places the species in north-western Gabon, including the Lambarene and Fougamou region, and describes a small area in the lower Ogowe and lower Ngoume drainages.

The habitat matters. FishBase describes swamps and brooks in coastal rainforest, while the WAK notes coastal rainforest swamps and brooks and gives type-locality water that was very soft. This is not a bright, hard-water community fish. In the aquarium, aim for a mature planted tank with dim areas, floating cover, leaf litter or botanical cover if you use it safely, fine plants, roots and gentle filtration.

Appearance and Display Value

Settled males show why this species is worth the careful setup. The body can glow greenish to yellow-green with red spotting and strongly coloured unpaired fins. The WAK notes heavy red margins to all unpaired fins, and Aquarium Glaser describes the Gabon killi as a colourful, hardy and approachable killifish that reaches about 5 cm.

Females are usually quieter in colour, so the display is strongest when the fish are settled, feeding well and not competing with fast tank mates. Use a dark or natural background, shaded planting and a calm routine. Under bright open lighting the fish may look washed out and spend too much time hiding.

Aquarium Setup

A covered aquarium is essential because killifish are excellent jumpers. For a pair or small group, use a stable planted aquarium of around 45-60 litres or more. Smaller breeding boxes can be used by experienced keepers, but a shop-bought display or first killifish setup should prioritise stability and room for cover.

• Use a tight lid with no gaps around filter pipes or cables.
• Keep flow gentle; sponge filters and baffled outlets work well.
• Add moss, fine-leaved plants, roots and floating plants for security.
• Use subdued lighting or shaded areas rather than a bare bright tank.
• Keep the aquarium mature, clean and quiet before adding the fish.

Indian almond leaves, alder cones or other botanicals can be useful if you already understand how they affect your water. They are not magic, but they can help create a softer, more sheltered rainforest-brook feel. Avoid sharp decor, boisterous tank mates and strong current.

Water Parameters

The old listing gave a broad 22-26 C supplier range. FishBase lists 22-25 C and pH 6.5-7.2, while Killi.co.uk breeding reports point to moderately soft acidic water at 20-23 C. A practical target for home care is 22-24 C, pH around 6.2-7.0 and low to moderate hardness.

• Temperature: 22-24 C preferred; avoid prolonged heat.
• pH: about 6.2-7.0, with stable conditions more important than chasing a number.
• Hardness: soft to moderately soft water is best.
• Water quality: ammonia and nitrite must stay at zero.

Acclimate slowly, especially if your water is harder than the supplier range. Sudden changes in hardness or temperature are a common reason small killifish fail after arrival.

Feeding

Aphyosemion gabunense is a small carnivorous killifish. Offer small live and frozen foods such as daphnia, cyclops, baby brine shrimp, mosquito larvae, grindal worm and finely chopped bloodworm where appropriate. Many individuals will also take fine quality granules or small soft prepared foods once settled, but live and frozen foods are the best route to colour, condition and breeding readiness.

Feed little and often. The fish are not built to compete with fast barbs, danios or pushy community fish, and uneaten rich foods can quickly spoil a small soft-water tank. Watch each fish feed, especially newly arrived females and subordinate males.

Temperament and Tank Mates

This is a peaceful, fairly shy killifish. It is usually best as a pair, trio or small species-focused group in a quiet planted aquarium. Males may display and posture, so use visual breaks and extra cover if keeping more than one male.

If you keep it with other fish, choose only very calm species that share similar soft-water conditions and will not dominate food. Tiny rasboras, small peaceful tetras or gentle bottom dwellers may work in larger planted tanks, but a species setup is the safest choice if you want full colour and breeding behaviour. Avoid fin nippers, fast feeders, large fish, aggressive dwarf cichlids and any fish likely to stress or outcompete them.

Breeding Notes

This is not a strict annual killifish. FishBase notes it is not seasonal, and Killi.co.uk reports long-term breeding where fry can appear with adults in moderately soft acidic water. WAK notes eggs laid in top mops, with later reports also finding eggs in peat fibre and bottom mops.

For a breeding attempt, condition the adults with small live foods and provide Java moss, fine plants or spawning mops. Eggs may be water-incubated, and specialist reports describe clear eggs hatching after roughly 18-22 days at about 72 F, with fry taking newly hatched brine shrimp once large enough. Breeding is possible, but the best results come from patient, species-focused husbandry rather than a busy community tank.

Common Mistakes

• Keeping the tank uncovered; even small gaps can be enough for a jump.
• Treating the supplied 3-4 cm size as the adult planning size.
• Using hard, bright, fast-flow community conditions.
• Keeping them with fast feeders that take all the food first.
• Calling them annual-style killifish and drying eggs by default.
• Letting warm summer temperatures stay high for long periods.

Who This Fish Suits

Yellow-Green Gabon Killie suits keepers who like quiet planted aquariums, soft-water species and fish with subtle behaviour rather than constant movement. It is a good choice for someone who can offer cover, small foods, stable water and a careful acclimation routine. It is less suitable for hard-water community tanks, uncovered aquariums or busy displays with large active fish.

Photo, Size and Delivery Notes

The exact Petra/source photo has been added to help you judge the fish honestly, while the existing aquarium visuals remain in the gallery for planted-tank context. Your fish may arrive as young stock around 3-4 cm and colour will continue to improve with settling, diet and maturity.

Eligible livestock orders are packed carefully and supported by the Tropical Fish Co Live Arrival Guarantee. Please be ready to receive the parcel, acclimate slowly and move the fish into a mature, covered aquarium with matching water conditions.

Sources Used For This Listing

Care details were checked against FishBase for distribution, maximum size, pH and temperature; AKA/WAK reference notes for Gabon locality, habitat and breeding; Killi.co.uk breeding reports for soft acidic water and long-term spawning; and Aquarium Glaser for aquarium trade size and general hardiness. These references are used to keep the page useful for aquarists, not to stuff search phrases.