Klein's Butterflyfish

Klein’s Butterflyfish, Chaetodon kleinii, is an attractive and adaptable saltwater fish known for its warm yellow to golden-brown coloration, pale vertical bands, and bold dark stripe running through the eye. Fine spotted or broken horizontal markings decorate the sides, while subtle blue coloration may develop around the upper head. Its deep, laterally compressed body and graceful swimming style give it the classic appearance associated with marine butterflyfish.

Native to a remarkably broad range spanning the Red Sea and East Africa across the Indo-Pacific to Hawaii and Samoa, with populations also occurring around the Galápagos Islands, this species inhabits deeper lagoons, channels, and seaward reefs. Adults are commonly found alone or in pairs and browse reef environments for soft coral polyps, algae, zooplankton, and other available foods.

Reaching approximately 6 inches as an adult, Klein’s Butterflyfish is a relatively manageable butterflyfish for a mature marine aquarium. Its generally peaceful temperament, willingness to accept a varied captive diet, and active personality make it an appealing addition to fish-only and fish-only-with-live-rock aquariums. Because coral tissue forms a significant part of its natural diet, however, it should not be considered reliably safe for a reef aquarium.

Quick Care Guide

Care Level: Easy to Moderate
Minimum Tank Size: 75 gallons
Temperament: Peaceful
Diet: Omnivore
Reef Safe: No
Region: Red Sea, Indo-Pacific, Hawaii, and Galápagos Islands
Scientific Name: Chaetodon kleinii

Tank Requirements

Provide a mature marine aquarium with established live rock, sheltered caves, and plenty of open swimming room. Klein’s Butterflyfish is an active cruiser that benefits from being able to move freely around and between rock structures while investigating surfaces for food.

Arrange the aquascape to provide several secure retreats without overcrowding the aquarium. Established rockwork is particularly beneficial because it offers natural browsing opportunities and can help newly introduced specimens acclimate more comfortably.

Moderate water movement, good oxygenation, efficient filtration, and stable water quality are recommended. Although this species is generally considered one of the more adaptable butterflyfish, it should still be introduced to a well-established saltwater aquarium rather than an unstable or newly cycled system.

A secure aquarium cover is advisable, particularly during initial acclimation when a startled fish may make sudden movements toward the surface.

Diet and Feeding

Klein’s Butterflyfish is an omnivorous reef browser that naturally consumes soft coral polyps, algae, zooplankton, and other small reef-associated foods.

In captivity, offer a varied diet including mysis shrimp, enriched brine shrimp, finely chopped shrimp, clam, mussel, krill, and quality frozen marine blends. Plankton-based preparations and foods formulated specifically for butterflyfish can also provide excellent nutritional variety.

Supplement meaty foods with spirulina-based preparations, marine algae, and high-quality omnivore pellets once the fish is readily accepting prepared foods. Newly introduced specimens may respond particularly well to frozen mysis or clam and mussel presented near established rockwork.

Feed two to three smaller meals per day when practical to support good body condition and complement its natural grazing and browsing behavior.

Temperament and Tankmates

Klein’s Butterflyfish is generally peaceful toward unrelated marine fish and works well in many appropriately sized community aquariums. Suitable tankmates include tangs, rabbitfish, peaceful wrasses, clownfish, gobies, cardinalfish, and compatible angelfish.

Territorial behavior can occur toward other butterflyfish, particularly similar species competing for the same feeding areas. A single specimen is the simplest arrangement for most aquariums.

Adults naturally occur singly or in pairs. An established compatible pair may be maintained in a sufficiently spacious aquarium, but two unrelated specimens should not automatically be expected to pair successfully.

Avoid overly aggressive tankmates that may continually harass the butterflyfish or prevent it from feeding.

Reef Compatibility

Klein’s Butterflyfish is not considered reef safe. Soft coral polyps form an important part of its natural diet, and captive specimens may actively nip at or consume desirable coral tissue.

Soft corals are particularly vulnerable, but stony corals, zoanthids, anemones, tubeworms, and other sessile invertebrates may also be investigated. Individual feeding preferences vary, but regular feeding does not guarantee that a specimen will ignore corals.

For predictable long-term care, a fish-only or fish-only-with-live-rock aquarium is the preferred environment.

Water Parameters

Temperature: 75–80°F
Specific Gravity: 1.024–1.026
pH: 8.1–8.4
Alkalinity: 8–12 dKH

Stable salinity, excellent oxygenation, and consistently clean water are more important than attempting to maintain an exact value within these ranges.

Common Considerations

• Not reef safe: Soft corals and other sessile invertebrates may be nipped or consumed.

• Mature rockwork is beneficial: Established surfaces provide natural browsing opportunities and shelter during acclimation.

• Varied diet: Offer both marine-based animal foods and algae-rich preparations for balanced nutrition.

• Butterflyfish compatibility: Territorial behavior may occur toward other butterflyfish, especially similar species.

• Frequent feeding: Two to three smaller meals per day help maintain body condition and support natural browsing behavior.