Can Bullseye Snakehead and Gertrude's Spotted Blue-eye Live Together?

Bullseye Snakehead is a highly aggressive species (10/10), while Gertrude's Spotted Blue-eye is peaceful (2/10). This notable difference means Bullseye Snakehead may occasionally assert dominance over Gertrude's Spotted Blue-eye.

Large aggression gap (8 points) between Bullseye Snakehead and Gertrude's Spotted Blue-eye increases stress risk for the more peaceful fish.

Bullseye Snakehead and Gertrude's Spotted Blue-eye both frequent the Top (Surface) and 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.

There is a critical concern: the Piscivore (Eats small/nano fish) behaviour of one fish directly conflicts with the Nano / Bite-sized (Predation Risk) trait of the other — piscivorous fish will prey on nano-sized tank mates..

Worth noting: Bullseye Snakehead is a known jumper, so a tight-fitting lid is essential.

The safe temperature window for both species falls between 22°C and 28°C. Aim for the midpoint of this range (around 25.0°C) for optimal comfort.

Both fish can tolerate a pH between 6 and 7.5. Maintaining a stable value within this band is more important than hitting an exact number.

For general hardness, the shared comfort zone is 5–15 dGH. Regular testing will ensure conditions stay within this range.

To house Bullseye Snakehead and Gertrude's Spotted Blue-eye together, plan for an aquarium of at least 5000 litres with a minimum length of 350 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: Driftwood (Digestion/Hiding), Plants - Floating, Plants - Densely covered, Leaf Litter/Blackwater. Meeting these requirements will help both species thrive.

Note a potential conflict in setup requirements: Bullseye Snakehead is a plant destroyer, which conflicts with Gertrude's Spotted Blue-eye's requirement for live plants. Compromise where possible or prioritise the more critical need.

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

Bullseye Snakehead and Gertrude's Spotted Blue-eye 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.