Can Electric Blue Johannii and Golden Wonder Killifish Live Together?

Electric Blue Johannii is a semi-aggressive species (8/10), while Golden Wonder Killifish is moderately assertive (6/10). This modest difference means Electric Blue Johannii may occasionally assert dominance over Golden Wonder Killifish.

In terms of spatial distribution, Electric Blue Johannii prefers the Middle (Open Water) and Bottom (Substrate) zones, whereas Golden Wonder Killifish occupies the Top (Surface) zone. Because they use different levels of the water column, territorial disputes are less likely and the tank will appear more balanced.

Worth noting: Golden Wonder Killifish is a known jumper, so a tight-fitting lid is essential.

The safe temperature window for both species falls between 24°C and 28°C. Aim for the midpoint of this range (around 26.0°C) for optimal comfort.

The pH requirements of Electric Blue Johannii (7.8–8.6) and Golden Wonder Killifish (6–7.5) do not overlap, making it impossible to satisfy both species simultaneously.

For general hardness, the shared comfort zone is 10–20 dGH. Regular testing will ensure conditions stay within this range.

To house Electric Blue Johannii and Golden Wonder Killifish together, plan for an aquarium of at least 199 litres with a minimum length of 90 cm. This recommendation combines the stricter species minimums with a community-load allowance so the pairing has realistic long-term space and filtration headroom.

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: Sand (Sifters), Established Algae (Otocinclus), Plants - Floating. 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.

Electric Blue Johannii and Golden Wonder Killifish are the kind of pair that can look acceptable in a shop but become a maintenance problem at home. The main risk is not a single number in the chart; it is the way incompatible behavior, water needs, or pressure on space compounds over time once both fish are established in the same tank.