Can Blue Emperor Tetra and Red Swamp Crayfish Live Together?

Blue Emperor Tetra is a peaceful species (2/10), while Red Swamp Crayfish is highly aggressive (9/10). This notable difference means Red Swamp Crayfish may occasionally assert dominance over Blue Emperor Tetra.

Large aggression gap (7 points) between Blue Emperor Tetra and Red Swamp Crayfish increases stress risk for the more peaceful fish.

In terms of spatial distribution, Blue Emperor Tetra prefers the Middle (Open Water) zone, whereas Red Swamp Crayfish occupies the Bottom (Substrate) zone. Because they use different levels of the water column, territorial disputes are less likely and the tank will appear more balanced.

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

Additional behavioural considerations to keep in mind: Shrimp eaters may also prey on very small nano fish.

Worth noting: Red Swamp Crayfish 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.

Both fish can tolerate a pH between 6.5 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 8–12 dGH. Regular testing will ensure conditions stay within this range.

To house Blue Emperor Tetra and Red Swamp Crayfish together, plan for an aquarium of at least 75 litres with a minimum length of 60 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: Plants - Densely covered, Leaf Litter/Blackwater, Driftwood (Digestion/Hiding), Shells (Breeding/Hiding). Meeting these requirements will help both species thrive.

Note a potential conflict in setup requirements: Red Swamp Crayfish is a plant destroyer, which conflicts with Blue Emperor Tetra'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.

Blue Emperor Tetra and Red Swamp Crayfish 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.

Feeding time deserves special attention with this pairing. Red Swamp Crayfish is a known shrimp eater and may prey on small invertebrates or nano fish like Blue Emperor Tetra.