Chrysiptera parasema
A hardy blue damselfish with a yellow tail, popular in aquariums.
Chrysiptera parasema, called the yellowtail damselfish, yellowtail blue damsel, or goldtail demoiselle, is a saltwater fish from the Indo-Pacific. Henry Weed Fowler first described it in 1918.
This small fish grows to 2.8–3 inches (7.1–7.6 cm) long. It has a spiny dorsal fin and a body that is flattened from side to side.
Its body is blue, with a bright yellow tail fin. In fish from Papua New Guinea, the yellow may spread onto the back edges of the anal and dorsal fins. The pelvic or pectoral fins can also be yellow. However, yellow never appears on the back or belly. A yellow belly likely means the fish is actually an Azure demoiselle, while yellow on the nose or chin suggests it is a blue devil damsel.
In the wild, these fish live in sheltered lagoons and inshore reefs, favoring dense coral groupings. They stay at depths between 3 and 52 feet (1–16 m).
Males hold territories near nesting sites, each containing eggs from previous females. Females inspect males and their territories, choosing a mate based on his size and the number of eggs already present. During evaluation, the female shows a light ring around her eye, and the male responds with his own displays. The next day, the female spawns with her chosen male. A single male may have up to 10,000 eggs from different females. Males often leave their territories to claim ones with more eggs, which makes them more attractive to females. Eggs hatch in up to four days, depending on temperature, and the male guards them. The larval stage lasts 10 to 50 days.
Chrysiptera parasema has chromatophores and can change color when stressed, turning darker to save energy. Adults are usually alone or in pairs, while juveniles stay in small groups. They are omnivores, eating plankton, algae, and small bottom-dwelling crustaceans.
In the aquarium trade, this fish is popular and often cheap, so it is recommended for beginners. Though sometimes used to cycle a tank, aquarists advise against this, suggesting live rock instead. A 30-gallon tank is the usual minimum for permanent housing. With proper care, they live 4–6 years, sometimes up to 15.
They prefer peaceful tank mates and plenty of hiding spots, since they are preyed upon in nature. They are active and less aggressive than most damselfish, but may harass more passive fish. They can be territorial with their own kind, especially when kept alone.
Quick Facts
- Taxon
- Chrysiptera parasema
Facts from the source article.
Lore & Background
Chrysiptera parasema is a small, laterally compressed marine fish with a spiny dorsal fin. Its coloring is predominantly blue, with a distinctive yellow caudal fin that may extend onto the back of the anal and dorsal fins, especially in specimens from Papua New Guinea. Yellow may also appear on the pelvic or pectoral fins, but never on the backs or bellies; a yellow belly suggests it is an Azure demoiselle, while yellow on the nose or chin indicates a blue devil damsel. In the wild, it inhabits sheltered lagoons and inshore reefs with densely populated coral groupings, at depths between 3 and 52 feet. Adults are usually solitary or in pairs, while juveniles form small groups. The species is omnivorous, feeding on plankton, algae, and small benthic crustaceans. It contains chromatophores and can darken when stressed to conserve energy.
Reader's Guide
Chrysiptera parasema is a significant species in the saltwater aquarium trade due to its hardiness and low cost, often recommended for novice marine aquarists to gain experience. Although sometimes used to cycle a tank, aquariums discourage this practice, advocating for live rock instead. A minimum tank size of 30 gallons is typically required for permanent housing, and with proper care, the fish can live 4–6 years or longer, up to 15 years. It prefers peaceful tank mates and abundant hiding spots, as it is frequently preyed upon in nature. While less aggressive than most damselfish, it may harass more passive fish and can be territorial with its own species, especially when kept singly. Aggression can be reduced by keeping them in small odd-numbered groups (three to seven), and they show schooling behavior in large groups. They must not be housed with larger predators like lionfish or grouper. In captivity, they prefer spirulina, flake foods, and mysis shrimp, and tend to feed near the bottom. Breeding occurs readily in captivity, with females laying around 300 eggs that hatch within 96 hours after lights out. Males guard the eggs, but eggs and larvae are difficult to rear, and predators like brittle stars, serpent stars, wrasses, and crabs will eat the eggs.
Did You Know?
- Males may abandon their territories to claim ones with more eggs, as this makes them appear more favorable to females.
- A yellow belly on a similar fish likely indicates it is an Azure demoiselle, not a yellowtail blue damsel.
- The larval stage of Chrysiptera parasema can last from 10 to 50 days.
- In the wild, males can have up to 10,000 eggs from different females in their territory.
More in Clownfish and Damselfish, Part 2 1-24
Spotted an error? Know more?
Reader corrections go straight into our review queue. Suggest an edit · How this site is sourced