Can Iridescent Shark and Marbled Bichir Live Together?

Iridescent Shark is a generally mild-mannered species (3/10), while Marbled Bichir is moderately assertive (6/10). This modest difference means Marbled Bichir may occasionally assert dominance over Iridescent Shark.

In terms of spatial distribution, Iridescent Shark prefers the Middle (Open Water) zone, whereas Marbled Bichir 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.

Worth noting: Marbled Bichir is nocturnal and will be most active after lights-out, naturally reducing daytime encounters. Also, Iridescent Shark 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 5–15 dGH. Regular testing will ensure conditions stay within this range.

To house Iridescent Shark and Marbled Bichir together, plan for an aquarium of at least 2000 litres with a minimum length of 250 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: Smooth Gravel (Sensitive Barbels), Sand (Sifters), Driftwood (Digestion/Hiding). 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.

This pairing usually fails when the tank is treated like a standard mixed community and the caution flags are ignored. Iridescent Shark and Marbled Bichir need extra room, more cover, and closer observation during the first few weeks so small aggression, feeding, or territory issues do not snowball into a long-term problem.