Paddlefin Wrasse

The Paddlefin Wrasse, Thalassoma lucasanum, is a brilliantly colored and highly active saltwater fish also commonly known as the Cortez Rainbow Wrasse. Juveniles display bold dark, yellow, and reddish coloration, while mature individuals undergo a dramatic transformation. Adult males are especially striking, developing a blue-green to violet head, rich reddish body coloration, and a prominent yellow band behind the head.

Native to the tropical Eastern Pacific, this species inhabits rocky and coral reef environments from the Gulf of California south to Peru, including the Galápagos Islands. In the wild, it actively patrols reef habitats while feeding on suspended plankton and small hard-shelled invertebrates. Its constant movement, vivid coloration, and outgoing behavior make it an impressive display fish for spacious marine aquariums.

The Paddlefin Wrasse is relatively hardy once established but becomes assertive as it matures. It is best suited to larger fish-only aquariums or carefully planned reef aquariums with robust tankmates. Corals are generally ignored, but ornamental crustaceans and other small invertebrates may be hunted.

Quick Care Guide

Care Level: Easy to Moderate
Minimum Tank Size: 75 gallons
Temperament: Aggressive
Diet: Carnivore / Planktivore
Reef Safe: With Caution
Region: Eastern Pacific – Gulf of California to Peru, including the Galápagos Islands
Scientific Name: Thalassoma lucasanum

Tank Requirements

Provide a spacious aquarium with substantial open swimming room and securely arranged rockwork containing caves, overhangs, and sheltered areas. The Paddlefin Wrasse is an energetic swimmer that spends much of the day actively exploring the aquarium, so adequate horizontal swimming space is particularly important.

A sand bed is recommended because this wrasse may bury itself when sleeping or frightened. Fine to moderately fine aquarium sand is preferable to coarse or sharp substrates.

Moderate to strong water movement and efficient filtration are appropriate for this active species. A tightly fitting aquarium lid is essential, as Thalassoma wrasses are powerful jumpers and may escape through surprisingly small openings around plumbing, cords, and overflow boxes.

Diet and Feeding

The Paddlefin Wrasse is primarily carnivorous, naturally feeding on suspended plankton, crustaceans, and other small reef-associated invertebrates.

Offer a varied captive diet consisting of mysis shrimp, enriched brine shrimp, krill, chopped shrimp, clam, squid, other marine seafood, quality frozen carnivore blends, and high-quality marine pellets or flakes.

Two to three smaller meals per day are beneficial when practical. This is an active species with a strong feeding response, and a varied diet helps maintain good body condition and coloration.

Temperament and Tankmates

The Paddlefin Wrasse is active, assertive, and potentially territorial, particularly as it matures. It is best housed with medium to large marine fish that are confident enough to tolerate its energetic behavior.

Avoid very timid, passive, or exceptionally small tankmates that may be intimidated or outcompeted for food. Particular caution should be used when keeping it with other Thalassoma wrasses or similarly shaped species, as territorial aggression can become significant.

A single specimen is the most predictable choice for most aquariums. If other assertive fish are planned, introducing the wrasse later in the stocking sequence can help reduce its opportunity to establish the entire aquarium as its territory.

Reef Compatibility

The Paddlefin Wrasse is generally coral-safe but should be considered reef safe with caution because of its natural predatory behavior toward small invertebrates.

SPS, LPS, and soft corals are generally not targeted. However, ornamental shrimp, small crabs, small snails, worms, and other mobile invertebrates may be investigated or eaten. The risk typically increases as the fish matures and becomes a more capable predator.

For reef aquariums centered around prized ornamental crustaceans or a diverse cleanup crew, this species may not be an appropriate choice.

Water Parameters

Temperature: 72–78°F
Specific Gravity: 1.024–1.026
pH: 8.1–8.4
Alkalinity: 8–12 dKH

Maintain stable temperature, salinity, and overall water quality. Consistency is more important than attempting to maintain one exact value within these ranges.

Common Considerations

• Adult coloration differs dramatically from the juvenile pattern, particularly in mature males.

• Provide a secure aquarium lid because this active wrasse is an accomplished jumper.

• Ample open swimming room is important despite its moderate adult length.

• Ornamental shrimp, small crabs, snails, worms, and other small invertebrates may become prey.

• Territorial and aggressive behavior may increase with maturity, especially toward other wrasses and similarly shaped fish.