Crown Squirrelfish - Sargocentron diadema

Crown Squirrelfish (Sargocentron diadema)

The Crown Squirrelfish is a striking nocturnal marine fish recognised for its vivid red colouration, large reflective eyes and contrasting pale horizontal markings. Most active during the evening and at night, it spends daylight hours sheltering beneath overhangs and within caves before emerging to hunt for food. Hardy once established but naturally predatory, it is best suited to mature marine aquariums with plenty of shaded rockwork and appropriately sized tankmates.

Common Name:
Crown Squirrelfish, Crowned Squirrelfish

Scientific Name (Latin):
Sargocentron diadema
Formerly also listed as Holocentrus diadema

Maximum Size:
Approximately 15–18 cm

Water Type:
Marine

Origin / Natural Habitat:
The Crown Squirrelfish occurs in tropical Indo-Pacific reef environments and is commonly associated with coral reefs, rocky ledges, caves and shaded reef structures.

It generally remains hidden during brighter daylight periods before becoming increasingly active after dark.

Water Parameters:
Temperature: 24–26°C
pH Range: 8.1–8.4
Salinity: SG 1.024–1.026
Nitrate: Low and stable
Ammonia/Nitrite: 0 ppm

Temperament:
Peaceful to Semi-Aggressive / Predatory

The Crown Squirrelfish is generally peaceful towards fish that are too large to swallow.

However, smaller fish and ornamental crustaceans may be regarded as prey, particularly after dark.

It is best maintained with peaceful to moderately robust tankmates of a suitable size.

Diet:
Carnivore / Nocturnal Predator

The Crown Squirrelfish naturally feeds on small crustaceans and other reef-associated animals.

In the aquarium, offer a varied diet including frozen mysis, chopped prawn, krill, squid and other suitable marine meaty foods.

Feeding during the evening or under subdued lighting can encourage more natural feeding behaviour.

Minimum Tank Size:
Approximately 250 litres

Provide substantial secure rockwork with caves, overhangs and shaded retreat areas.

Behaviour & Activity:
The Crown Squirrelfish is primarily nocturnal and may spend much of the day sheltering beneath rockwork or inside caves.

As lighting levels decrease, it becomes increasingly active and will venture into open areas in search of food.

Its large eyes are well adapted to low-light conditions.

Several individuals may sometimes be maintained in a sufficiently spacious aquarium with adequate shelter and carefully managed territories.

Reef Safe:
With Caution

The Crown Squirrelfish does not normally damage healthy coral tissue.

However, ornamental shrimp, small crabs and other suitably sized mobile invertebrates may be eaten.

It is therefore best considered reef safe with caution.

Special Requirements or Care Notes:
Provide a mature marine aquarium with stable water chemistry, excellent filtration and numerous caves or shaded overhangs.

Avoid very small fish and ornamental crustaceans where their safety is a priority.

Subdued areas within the aquascape will help the fish settle and display more natural behaviour.

New specimens may remain hidden during the day and should be monitored carefully to ensure they are feeding successfully.

A varied carnivorous diet should be offered regularly, with evening feeding particularly beneficial.

Care should be taken around the fish's dorsal spines when handling or transferring specimens.

Suitable for:
Intermediate

Availability:
Availability can vary depending on season, collection area and supplier.

All images are a visual representation of the fish you will receive, made to be as accurate as possible. Please note that Mother Nature is a wonderful thing, and variation in patterns and colours will occur — that is part of the unique beauty of these animals.