Can Aequidens diadema (Diadem Cichlid) and Silver Hatchetfish Live Together?

Aequidens diadema (Diadem Cichlid) is a moderately assertive species (6/10), while Silver Hatchetfish is peaceful (1/10). This notable difference means Aequidens diadema (Diadem Cichlid) may occasionally assert dominance over Silver Hatchetfish.

In terms of spatial distribution, Aequidens diadema (Diadem Cichlid) prefers the Middle (Open Water) and Bottom (Substrate) zones, whereas Silver Hatchetfish occupies the Top (Surface) zone. Because they use different levels of the water column, territorial disputes are less likely and the tank will appear more balanced.

Worth noting: Silver Hatchetfish 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 Aequidens diadema (Diadem Cichlid) and Silver Hatchetfish 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 23°C and 28°C. Aim for the midpoint of this range (around 25.5°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 5–12 dGH. Regular testing will ensure conditions stay within this range.

To house Aequidens diadema (Diadem Cichlid) and Silver Hatchetfish together, plan for an aquarium of at least 200 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: Sand (Sifters), Driftwood (Digestion/Hiding), Plants - Floating. Meeting these requirements will help both species thrive.

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