Species description

Care, breeding and tankmates

Fish profile

Temperament

Semi-aggressive

The Semicircle Angelfish is a remarkably bold, highly territorial fish that will aggressively assert dominance over the aquarium. It is notoriously intolerant of other angelfish and any species exhibiting similar colors or body shapes. To mitigate severe tank-wide conflict, it is strongly advised to add this dominant fish as the absolute final resident.

Diet

Omnivore

Their natural diet consists heavily of marine sponges, tunicates, and a variety of benthic algae. In captivity, it is imperative to feed them specialized commercial angelfish diets containing real marine sponge extract. This strict requirement should be supplemented with frequent feedings of spirulina, marine nori, and high-quality meaty foods like mysis shrimp.

Sex ratio

Solitary

There are no highly apparent external sexual dimorphisms to reliably distinguish male and female Semicircle Angelfish. Due to their extreme, uncompromising intraspecific aggression, keeping more than one specimen per tank is strictly prohibited. Co-housing multiple adults is a highly dangerous endeavor only possible in massive public aquarium settings.

Feeding frequency

Twice daily

To properly satiate their high metabolism and constant grazing behavior, they must be fed two to three times daily. Providing frequent, small meals significantly helps to naturally reduce their aggression towards other tank inhabitants. Offering a daily supply of seaweed on a clip closely simulates their natural foraging patterns.

Bioload

The Semicircle Angelfish is a rapidly growing, heavy-eating marine fish that introduces a very high bioload to the aquarium. It requires extremely powerful mechanical and biological filtration, alongside a highly rated protein skimmer. Consistent, large-volume water changes are absolutely vital to control nitrate accumulation and maintain optimum water clarity.

Flow

Stagnant

Originating from highly active reef slopes across the Indo-Pacific, they strongly prefer moderate to strong, turbulent water movement. Robust water flow ensures the large aquarium remains thoroughly oxygenated and helps keep waste particles safely suspended. Wavemakers are highly recommended to create erratic, varied currents that stimulate natural swimming behaviors.

Reproduction

Oviparous

Breeding the Semicircle Angelfish in a home aquarium is considered effectively impossible due to their pelagic broadcasting reproductive strategy. In nature, pairs quickly ascend to the surface at dusk, releasing massive clouds of eggs into the ocean currents. Rearing the microscopic larvae requires highly sophisticated commercial aquaculture facilities and meticulously cultured live foods.

Compatibility & tankmates

As they mature, Semicircle Angelfish transition from peaceful juveniles to highly aggressive and territorial adults. They should only be kept with other large, robust, and assertive species like triggerfish, large wrasses, and sturdy tangs. They are entirely destructive in a reef environment, eagerly consuming most corals, sponges, and delicate invertebrates.

Tank level

All levels

This highly active species freely utilizes the entire water column, aggressively patrolling its established territory from top to bottom. They require an enormous aquarium offering vast, open swimming spaces alongside substantial, intricate rockwork. Large, cavernous hiding spots are absolutely necessary for them to sleep and securely retreat from perceived threats.