Lamarck Angelfish - Female - Genicanthus lamarck
Lamarck Angelfish - Female - Genicanthus lamarck
Goes well with:
FAQs Answers to the most common questions.
Is the Lamarck Angelfish truly reef-safe, and what corals or invertebrates is it most likely to bother?
The Lamarck Angelfish (Genicanthus lamarcki) is one of the most reef-friendly angelfish species you can keep. Unlike most “large angels,” it usually ignores SPS, LPS, soft corals, clams, and most ornamental inverts. That said, no angelfish is 100% guaranteed: an individual may occasionally sample zoanthids, fleshy LPS, or clam mantles if underfed or stressed. In a well-fed, mature reef, it’s generally considered a very safe choice.
How can I tell male and female Lamarck Angelfish apart, and do they change sex in captivity?
Yes, they are protogynous hermaphrodites, meaning they start as females and the dominant fish can transition to male. Females are typically darker overall with a more uniform pattern, while males develop stronger contrast, a more striking yellow-and-blue tail pattern, and a more pronounced facial mask. In a pair or group, if the male is removed, the largest female may eventually transform into a male over time. This is especially useful if you want to keep a bonded pair, but the transition is not immediate.
What size tank does a Lamarck Angelfish need, and is it okay in a standard mixed reef?
A single Lamarck Angelfish should ideally be kept in at least 125 gallons, with 180+ gallons being better if you want long-term stability and more natural swimming space. They are active open-water swimmers and appreciate strong flow and plenty of open area. They do very well in a mature mixed reef, especially with rockwork that provides shelter but doesn’t crowd the tank. They are not a good fit for small tanks or cramped aquascapes.
What should I feed a Lamarck Angelfish to keep its color and prevent it from picking at corals?
Feed a varied diet heavy on marine-based foods: mysis shrimp, enriched frozen brine, chopped seafood, angel preparations with sponge material, and quality pellets or flakes with marine protein. Seaweed/nori is also helpful. These fish are plankton-feeders in the wild, so multiple small feedings per day are ideal. A well-fed Lamarck is much less likely to investigate corals or nip at tankmates’ food.
Is the Lamarck Angelfish aggressive, and what fish does it usually do best with?
Lamarck Angelfish are generally peaceful for an angelfish, but they can still be assertive toward other angelfish, similarly shaped fish, and sometimes other plankton-feeding open-water species. They usually do best with tangs, wrasses, anthias, larger gobies, and other calm-to-moderate community reef fish. Avoid combining them with highly territorial dwarf angels or multiple large angels unless the tank is very large and stocked strategically. Introduce them carefully, ideally after more aggressive fish have already settled.
All listed sizes are approximate, not guaranteed, and may vary slightly.
The female Lamarck Angelfish (Genicanthus lamarck), also known as the Blackstriped Angelfish, is an elegant marine angelfish distinguished by a silvery-white to pale gray body marked with bold horizontal black stripes. Females display particularly strong striping, a dark-edged dorsal profile, white pelvic fins, and a finely spotted or patterned tail, giving them a clean, high-contrast appearance that stands out beautifully against reef rockwork.
Native to the Indo-West Pacific, this species occurs from the Indo-Malayan region east to Vanuatu, north to southern Japan, and south to the Great Barrier Reef. In nature, Lamarck Angelfish inhabit reef crests and deeper reefs near steep slopes, where they often swim above the reef and feed on plankton in the water column.
Unlike many larger angelfish, Genicanthus species are primarily planktivorous and are among the more dependable choices for a reef aquarium. Their generally peaceful temperament, active swimming behavior, and excellent reef compatibility make the female Lamarck Angelfish an attractive centerpiece or community saltwater fish for a spacious reef or fish-only aquarium.
Quick Care Guide
Care Level: Moderate
Minimum Tank Size: 125 gallons
Temperament: Peaceful
Diet: Planktivore / Omnivore
Reef Safe: Yes
Region: Indo-West Pacific
Scientific Name: Genicanthus lamarck
Tank Requirements
The Lamarck Angelfish is an active open-water swimmer and should be provided with a mature aquarium of at least 125 gallons. Adults can approach approximately 10 inches in total length, so long-term housing should prioritize horizontal swimming room rather than filling the aquarium entirely with rockwork.
Provide substantial live rock around the sides and back of the aquarium, leaving broad areas of open water for cruising. Caves, overhangs, and crevices give the fish secure retreat areas during acclimation and at night. A well-established aquarium is preferred, particularly because mature rockwork provides additional natural feeding opportunities and a more stable environment.
Moderate to strong water movement, good oxygenation, efficient filtration, and consistent water quality are ideal. Because this species spends much of its time swimming in the water column, an aquarium layout that combines reef structure with generous open space will best accommodate its natural behavior.
Diet and Feeding
Lamarck Angelfish are primarily planktivorous in the wild, feeding on suspended plankton above the reef. In captivity, they adapt well to a varied marine diet and should receive several different food types to maintain body condition and coloration.
Offer mysis shrimp, enriched brine shrimp, finely chopped marine seafood, copepod-based foods, quality frozen marine blends, small sinking or slow-sinking pellets, and appropriately sized flakes. Spirulina and other marine algae-based foods can also be included for additional nutritional variety.
Two to three smaller feedings per day are preferable when possible, especially for newly introduced specimens accustomed to feeding repeatedly on plankton throughout the day.
Temperament and Tankmates
The female Lamarck Angelfish is generally peaceful and considerably less territorial than many Pomacanthus or Holacanthus angelfish. It is well suited to community aquariums containing peaceful to moderately assertive marine fish such as tangs, wrasses, anthias, gobies, blennies, rabbitfish, and other compatible reef species.
It may be maintained singly or, in appropriately sized aquariums, as part of a compatible pair or harem consisting of one male with multiple females. Avoid keeping multiple established males together unless the aquarium is exceptionally large and carefully managed.
Like other Genicanthus angelfish, Lamarck Angelfish have a socially influenced sex structure. Females are capable of transitioning toward male coloration and sex when social conditions favor the change, which is worth considering when planning pairs or groups.
Reef Compatibility
The Lamarck Angelfish is considered reef safe and is one of the better angelfish choices for coral-dominated aquariums.
Because its natural feeding strategy focuses heavily on plankton captured in the water column, it is much less inclined to graze directly on corals than many other marine angelfish. It is generally compatible with SPS and LPS corals, soft corals, zoanthids, clams, and most ornamental invertebrates.
As with virtually any individual fish, occasional investigative picking is possible, but persistent coral predation is not considered typical behavior for this species.
Water Parameters
Temperature: 75–80°F
Specific Gravity: 1.024–1.026
pH: 8.1–8.4
Alkalinity: 8–12 dKH
Stable water chemistry, strong oxygenation, and consistently good water quality are more important than maintaining one exact number within these ranges. Avoid rapid changes in temperature, salinity, or pH during acclimation.
Common Considerations
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Active swimmer: Provide extensive open water in addition to caves and established reef rockwork.
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Adult size: This species can approach approximately 10 inches and requires a spacious aquarium for long-term care.
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Frequent feeding: Its natural planktivorous lifestyle makes multiple smaller meals especially beneficial.
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Social sex change: Females may transition toward male coloration and sex depending on the social structure of the aquarium.
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Excellent reef candidate: Lamarck Angelfish are among the more reliably coral-compatible marine angelfish, making them particularly desirable for larger reef systems.
