Can Denison Barb (Roseline Shark) and Flowerhorn Cichlid Live Together?

Denison Barb (Roseline Shark) is a generally mild-mannered species (3/10), while Flowerhorn Cichlid is highly aggressive (10/10). This notable difference means Flowerhorn Cichlid may occasionally assert dominance over Denison Barb (Roseline Shark).

Large aggression gap (7 points) between Denison Barb (Roseline Shark) and Flowerhorn Cichlid increases stress risk for the more peaceful fish.

Denison Barb (Roseline Shark) and Flowerhorn Cichlid both frequent the Middle (Open Water) and Bottom (Substrate) 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: Denison Barb (Roseline Shark) 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 Denison Barb (Roseline Shark) and Flowerhorn Cichlid 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 26°C and 26°C. Aim for the midpoint of this range (around 26.0°C) for optimal comfort.

Both fish can tolerate a pH between 7.4 and 7.8. Maintaining a stable value within this band is more important than hitting an exact number.

For general hardness, the shared comfort zone is 9–20 dGH. Regular testing will ensure conditions stay within this range. An aquarium test kit is recommended for monitoring.

To house Denison Barb (Roseline Shark) and Flowerhorn Cichlid together, plan for an aquarium of at least 336 litres with a minimum length of 120 cm. This accounts for the larger species' space requirements with an additional 20 % buffer to reduce territorial tension.

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, Driftwood (Digestion/Hiding), Smooth Gravel (Sensitive Barbels), Sand (Sifters). Meeting these requirements will help both species thrive.

Note a potential conflict in setup requirements: Flowerhorn Cichlid is a plant destroyer, which conflicts with Denison Barb (Roseline Shark)'s requirement for live plants. Compromise where possible or prioritise the more critical need.

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