Ruby Anthias

Ruby Anthias: The Open-Water Reef Aggregator

The Ruby Anthias (Paranthias colonus), also known as the Creole Fish, is a unique and fascinating member of the grouper family (Serranidae). Unlike most groupers that hide in caves or stay close to the substrate, this species has evolved a slender, streamlined body and a deeply forked tail, adapting to a life of active, open-water swimming. Sporting a beautiful reddish-brown to olive-pink coloration often accented by small, bright spots along its back, it brings captivating motion and school-like behavior to large marine aquariums.

Native to the Eastern Pacific Ocean, ranging from the Gulf of California down to Peru and around the Galápagos Islands, this fish can grow to an impressive maximum length of about 12 to 14 inches (30-35 cm). Because they are high-energy, schooling fish that spend their time cruising the water column in search of food, they require a tremendous amount of swimming space. A minimum aquarium size of 180 gallons is required to house a single specimen, though a much larger tank is necessary if you intend to keep a small group.

The Ruby Anthias is generally peaceful toward other fish that are too large to swallow, making it an excellent addition to large community setups or predator-focused tanks. They are hardy and adaptable, but because of their active lifestyle, they require strong water movement, highly efficient filtration, and a tightly fitted lid, as they can be prone to jumping when startled.

Diet & Compatibility:

• Diet: This fish is a dedicated Planktivore. Unlike its ambush-predator grouper cousins, it feeds on zooplankton drifting in the current. In the aquarium, it should be fed a varied diet of meaty frozen foods, including mysis shrimp, krill, finely chopped squid, clams, and high-quality marine pellets. Because of their fast metabolism and constant swimming, they should be fed at least twice a day.
• Feeding: They are enthusiastic eaters and will quickly learn to rush to the surface during feeding time. Ensure that enough food disperses throughout the water column so all tankmates get a share.
• Reef Compatibility: It is Reef Safe With Caution. They will completely ignore stony and soft corals, anemones, and polyps. However, they are opportunistic predators and will systematically hunt down and consume small ornamental shrimp, crabs, and very small fish.
• Temperament: It is Peaceful to Semi-Aggressive. It is peaceful toward larger, robust tankmates such as tangs, large angels, triggerfish, and larger wrasses. It can be kept singly or in a group if introduced simultaneously to a massive system. Avoid housing it with tiny, passive fish like neon gobies or micro-chromis, which may become an accidental snack.

Quick Facts

• Scientific Name: Paranthias colonus
• Primary Common Name: Ruby Anthias or Pacific Creolefish
• Other Common Names: Creole Fish, Southern Creole Fish
• Origin: Eastern Pacific (Gulf of California to Peru)
• Max Size: 12-14 inches (30-35 cm)
• Temperament: Peaceful to Semi-Aggressive
• Diet: Planktivore / Carnivore
• Minimum Tank Size: 180+ Gallons
• Reef Compatibility: With Caution (Will eat small invertebrates and tiny fish)