Can Ajamaru Rainbowfish and Electric Blue Johannii Live Together?

Ajamaru Rainbowfish is a peaceful species (2/10), while Electric Blue Johannii is semi-aggressive (8/10). This notable difference means Electric Blue Johannii may occasionally assert dominance over Ajamaru Rainbowfish.

Large aggression gap (6 points) between Ajamaru Rainbowfish and Electric Blue Johannii increases stress risk for the more peaceful fish.

Ajamaru Rainbowfish and Electric Blue Johannii both frequent the Middle (Open Water) region of the setup. This overlap can increase competition for space, so providing ample room and cover is important to keep both species comfortable.

Worth noting: Ajamaru Rainbowfish is a known jumper, so a tight-fitting lid is essential.

To improve the chances of a peaceful coexistence in this community tank: Provide a significantly larger tank (at least 50% more volume than the minimum) to allow both Ajamaru Rainbowfish and Electric Blue Johannii to establish separate territories. Add plenty of line-of-sight breaks using driftwood, rocks, and dense planting to reduce territorial confrontations. A larger aquarium with ample hiding spots can help diffuse aggression and give the less dominant fish space to retreat.

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.

Both fish can tolerate a pH between 7.8 and 8.5. Maintaining a stable value within this band is more important than hitting an exact number.

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

To house Ajamaru Rainbowfish and Electric Blue Johannii together, plan for an aquarium of at least 235 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.

Because this pairing requires extra vigilance, include plenty of hiding spots — caves, driftwood, and dense plant clusters — so the less dominant fish can retreat when needed.

Specific environmental needs for this combination include: Plants - Densely covered, Sand (Sifters), Established Algae (Otocinclus). Meeting these requirements will help both species thrive.

Note a potential conflict in setup requirements: Electric Blue Johannii is a plant destroyer, which conflicts with Ajamaru Rainbowfish's requirement for live plants. Compromise where possible or prioritise the more critical need.

Both species do well with moderate (standard) water movement, so a standard filtration setup rated for the tank volume should suffice.