Species description

Care, breeding and tankmates

Fish profile

Temperament

Aggressive

The temperament of this fish is markedly aggressive and strongly territorial toward anyone who approaches its rocky living space. It displays remarkable boldness and combativeness, constantly patrolling the tank and decisively defending its favorite area. In large aquariums rich in visual barriers, its aggression can be successfully managed by housing suitable tankmates.

Diet

Omnivore

This species is omnivorous and requires a varied and balanced diet to remain healthy. In the wild, it feeds mainly on filamentous algae and small benthic crustaceans. In the aquarium, it accepts high-quality commercial pellets and flakes with a vegetable base enriched with spirulina, as well as frozen foods such as mysis, brine shrimp, and chopped krill. Offering both protein and plant-based foods regularly prevents intestinal issues and supports its remarkable hardiness.

Sex ratio

Flexible

Solitary or mated pairs

Feeding frequency

Twice daily

It is recommended to feed this fish once or twice daily with amounts that can be consumed within a few minutes. Moderate but regular portions help satisfy its dynamic metabolism and prevent excess organic waste in the tank. Feeding at constant intervals helps reduce territorial excitement associated with nutrition.

Bioload

The one-spot demoiselle creates a moderate bioload in the marine aquarium, directly tied to its highly active nature and territorial behavior. Because they burn significant energy defending their claimed space and foraging for food, they require frequent feedings that translate to elevated waste production. An established aquarium with strong mechanical and biological filtration will easily process their output. However, in smaller nano setups, their bioload might require more frequent water changes to maintain ideal water parameters.

Flow

Strong

In the wild, it inhabits areas exposed to strong currents and surge, preferring a strong and vigorous water flow in the aquarium as well. Efficient water movement supports high oxygenation, which is fundamental for its overall well-being. However, it is recommended to set up the live rock to provide deep cracks and caves where the fish can take refuge and rest sheltered from the current.

Jump risk

No

Reproduction

Oviparous

This oviparous species exhibits typical damselfish reproductive behavior, depositing adhesive benthic eggs on solid surfaces. The male takes care of preparing and cleaning the nesting site, aerating the eggs and vigorously defending the clutch from any predators until hatching. Rearing the fry in the aquarium is extremely complex due to the pelagic larval stage and the microscopic size of the larvae, which require fresh cultures of rotifers.

Compatibility & tankmates

Highly aggressive

This species is extremely aggressive and territorial, especially as it ages, making it incompatible with docile, slow fish or other members of its own family. It is completely safe for reef corals and can be kept in tanks with equally robust and active species, such as dottybacks, large angelfish, tangs, and triggerfish. It is recommended to introduce it as the last guest in the aquarium to prevent excessive territorial dominance.

Tank level

All levels

This demoiselle strongly favors the middle to lower levels of the aquarium, continuously patrolling the rockwork to defend its territory. They are fiercely attached to specific caves or crevices and rarely venture into the open upper water column unless actively feeding. Their entire social and defensive life is centered around the reef structure, making them a predominantly benthic-adjacent swimmer. Aquarists should ensure the tank provides ample rocky structures to support their lower-level territorial habits.