Bluestripe Flasher Wrasse

Bluestripe Flasher Wrasse

The Bluestripe Flasher Wrasse (Paracheilinus mccoskeri), or McCosker's flasher wrasse, is a small, jewel-like reef fish whose males put on one of the best displays in the hobby. Normally orange and pastel with fine blue lines, a courting or competing male "flashes" — erecting his fins and lighting up with electric blues, reds and yellows for a few dazzling seconds. Peaceful, reef-safe and hardy, it is a superb, active fish for community reef aquariums.

It is at its most spectacular kept as a male with several females, where the constant low-level competition keeps the male flashing.

Natural Habitat & Origin

Paracheilinus mccoskeri is found in the Indian Ocean and adjacent western Pacific, where it lives in loose aggregations over reef slopes and rubble, feeding on zooplankton in the water column. Males display to harems of females above the reef, especially toward dusk.

In the aquarium it wants open swimming space above the rock for its mid-water swimming and displays, with some rockwork for shelter.

Care Requirements

Maintain stable marine conditions: salinity around 1.024–1.026, pH 8.1–8.4, and a temperature of about 24–26°C (75–79°F). Reaching only about 8 cm (3 inches) and best kept as a small group (one male with two or more females), it suits a tank of around 115 litres (30 US gallons) or more. A secure, gap-free lid is essential — flasher wrasses are notable jumpers.

It is hardy and undemanding once settled, and accepts prepared foods readily.

Diet & Feeding

The Bluestripe Flasher Wrasse is a micro-carnivore, feeding on zooplankton in the wild. It accepts aquarium foods well: offer frequent small meals of frozen mysis and enriched brine shrimp, finely chopped seafood and quality small marine pellets and flakes. Several small feedings a day suit its fast metabolism and keep colours vivid.

Behavior & Temperament

This is a peaceful, active fish that poses no threat to tankmates. Males may display to and gently spar with one another, so keep a single male unless the tank is large; a male with several females is ideal and brings out the best flashing behaviour. It spends its day swimming busily in open water and diving into the rocks at night, where it may sleep in a mucus cocoon.

Tank Mates

Good companions are other peaceful reef fish — clownfish, gobies, other small wrasses, anthias, cardinalfish and similar. Avoid aggressive or boisterous species that will intimidate it. It is fully reef-safe, leaving corals and ornamental invertebrates alone, making it one of the best small, colourful additions to a peaceful reef.

Breeding

Paracheilinus mccoskeri spawns readily in the wild in pelagic fashion, and aquarium spawning is occasionally observed, but rearing the tiny larvae is difficult and rarely achieved at home. Trade specimens are wild-collected.

Common Health Issues

The Bluestripe Flasher Wrasse is hardy but, like all marine fish, can be affected by marine ich (Cryptocaryon irritans) and marine velvet (Amyloodinium ocellatum) under stress. Quarantine new arrivals, keep water quality stable, secure the lid against jumping, and feed frequently. Given those basics — ideally as a small harem — it is a brilliant, beginner-friendly and endlessly entertaining reef fish.