The fish species Genicanthus watanabei is known under several different names in English, including Watanabe's angelfish, Watanabe's angel, Watanabe angelfish, Watanabe angel, Watanabe's lyretail angelfish, and Blackedged angelfish.
Genicanthus watanabei has not been evaluated for the IUCN Red List of Threatened Species.
Geographical range, habitat and habits
Watanabe's angelfish is found in the Pacific Ocean. Its range stretches from Taiwan to the Tuamotu Archipelago in French Polynesia. Southwards, this species can be found up to the Ryukyu Islands of Japan. Northwards, you can encounter Watanabe's angelfish down to New Caledonia and the Austral Islands.
Watanabe's angelfish inhabits current-swept outer reef slopes and drop-offs. It is found fairly deep down in the ocean, at a depth of 70-265 feet / 21-81 meters. It lives in harems consisting of 2-5 specimens.
Size and appearance
The largest scientifically measured Watanabe angelfish was 15.0 cm / 5.9 in. Females are usually smaller than males.
The female is light blue and decorated with a vertical black bar over the eye and spots on her forehead. On her caudal fin lobes, you can see a broad submarginal band. The male is light blue and sports eight black stripes on the lower 2/3 of his body. Both sexes have a broad submarginal band on dorsal and anal fins.
Watanabe's Angelfish care
Watanabe's angelfish feeds primarily on zooplankton. This feeding habit makes it less “rock-bound” than most other species of angelfish and you can often see it swimming around in mid-water in the aquarium. It is a powerful swimmer and should only be kept in aquariums with plenty of swimming room. Keeping it in an aquarium smaller than 100 gallons / 375 liters is not recommended. The aquarium must also be large enough to accommodate suitable hiding spots. When newly introduced to an aquarium, Watanabe's angelfish is normally quite shy and will spend a lot of time hidden, but it will gradually become bolder and bolder as it gets used to its new home and eventually adopt a more pelagic living style.
If you want to make your Watanabe's angelfish look as appealing as possible in the aquarium, install metal halide lights instead of fluorescent lighting. A brightly lit aquarium can however make the fish feel a bit uncomfortable at first (its dept range is 70-265 feet / 21-81 meters), so it can be a good idea to go for less sharp lighting while the fish is acclimatizing itself to its new tank.
Watanabe's angelfish can be housed with other peaceful fish in a community aquarium. Unlike many other species of angelfish, Watanabe's angelfish will tolerate other angels in the aquarium. It should ideally not be housed with active zooplankton feeders since they might compete for food with each other.
In the wild, the Watanabe's angelfish lives in pairs or in harems consisting of one male and several females. Keeping it in such configurations in the aquarium is a good idea, but don’t forget that this is a protogynous hermaphrodites. All specimen start out as females and each female is capable of changing into a male. Since most specimens stay female in the ocean, males are rare in the aquarium trade and usually more expensive. You can purchase females only instead and hope for one of them to change into a male. (Another reason why females are more common in the trade is that they are smaller than males, so you can pack more fish into a box if you ship females only.) Keeping two males together is not recommended since they will fight each other.
Watanabe's angelfish feeds on zooplankton and is known to leave corals, sponges and most other types of marine life alone. It is therefore considered reef safe, but certain individuals may start attacking reef creatures. Such problems are however very uncommon.
The recommended water temperature for this species is 72-78º F / 22-25.5º C. Keep the pH-value in the 8.1-8.4 range and the specific gravity at 1.020-1.025.
Feeding Watanabe's Angelfish
Watanabe's angelfish feeds primarily on zooplankton. As mentioned above, it is a pelagic feeder that spends a lot of time out in the open, but it is also known to investigate rocks and corals in the aquarium in search of food.
The Watanabe angelfish is known to accept most types of food, including pellets and flakes. You don’t have to give it zooplankton, but it needs plenty of meaty foods to stay healthy. You can for instance serve brine shrimp, mysid shrimp, and chopped seafoods (shellfish, shrimps, clams ectera). It will also need some green foods in its diet, preferably in the form of fresh and dried marine algae and spirulina. In addition to this, it is a good idea to add a vitamin rich flake or pellet to the diet. This species will also appreciate angelfish preparations.
Ideally feed your Watanabe angelfish many small portions of food instead of just one or two big meals per day.
Breeding Watanabe's Angelfish
Watanabe's angelfish have distinct male and female colour morphs. It is an protogynous hermaphrodite, which means that all individuals are female at first but have the capacity to change into males.
The female is light blue with a vertical black bar above the eye and dots on her forehead. On her caudal fin lobes, you can see a broad submarginal band. The male fish is light blue with eight black stripes on the lower 2/3 of his body. Both males and females have a broad submarginal band on anal and dorsal fins. As mentioned above, females are usually smaller than males.
The Watanabe angelfish is an egg-scattering species.
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Cherub Angelfish – Centropyge argi
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Emperor Angelfish – Pomacanthus imperator
Flame Angelfish – Centropyge loricula
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Koran Angelfish – Pomacanthus semicirculatus
Lamarck's Angelfish – Genicanthus lamarack
Potter's Angelfish – Centropyge potteri
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Rock Beauty Angelfish – Holacanthus tricolor
Rusty Angelfish – Centropyge ferrugata