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 Text and photos copyright John P. Hoover

past fishes of the month


Sarotherodon melanotheron


Dear Mr. Hoover,
     I have just returned from a week's vacation in O'ahu. While there I observed a fish that I could not identify. It was not in your book "Hawaii's Fishes" or any other sources that I have access to. I was wondering if you could help me identify this mystery fish. The fish that I observed was first seen from the shore at the breakwater at "Queen's Beach" in Waikiki by Kapiolani Park. I also saw many of these fish another day in the harbor by Magic Island. The actual fish itself was about 5-8 inches long and mottled green-brown to almost black in some individuals. The fish had very large eyes (much like a Bigeye Emperor), a blunt snout, and dark marking behind the gills. It was swimming out in the open near the surface in a small school. After snorkeling with them and trying to identify them, I asked a local what they were called and he said they were locally called Talipo (spelling??), but I have found no reference to them in any of the sources I have looked at. So as I said, if you have enough time to help me identify this mystery fish that would be great.

San Jose, California

Dear James,
     They sound like Tilapia - a freshwater fish from Africa which was introduced to Hawaii and has a limited ability to survive in salt water. They are common near shore in Waikiki. I saw some there just the other day, in fact, and said to myself that I should try to get a photo and put them into the next edition of my fish book. I'm not sure at this point which species of Tilapia they are. Thanks for the reminder to look into this!

Happy New Year,

Blackchin Tilapia - Queen's Beach, Waikiki, O`ahu. 3 ft.

TILAPIAS (family Cichlidae)
      Tilapias are a group of hardy, fast-growing fresh and brackish water fishes native to Africa and the Near East which have been widely spread throughout the tropics for food and aquaculture. Many are, or were at one time, classified in the genus Tilapia, thus the common name. All tilapias are members of the enormous freshwater fish family Cichlidae--the second-largest fish family in the world and one of the most diverse. Some cichlids are quite colorful. Because they are easy to breed, many have entered the freshwater aquarium trade. Over the years, aquarists have released a surprising number of cichlid species into Hawaii's streams and reservoirs, where some have become established. Most of the tilapias, however, were deliberately introduced beginning with four species in the early 1950s brought in control vegetation in irrigation canals, for possible use as baitfish, and also for human food and recreation. Of these introduced species, the Mozambique Tilapia (Oreochromis mossambicus) was at first the most successful, becoming almost ubiquitous in the fresh and brackish waters of the Islands. Salt-tolerant, it even entered the marine environment to some degree. However, it has since been largely displaced by the even more hardy and adaptable Blackchin Tilapia (Sarotherodon melanotheron), which was introduced accidentally in 1965.
      Sometimes called the "saltwater tilapia", the Blackchin has the ability to survive, maybe even to breed, in pure seawater and can be seen off sheltered beaches and in lagoons around O`ahu and possibly the other islands. We do not yet know yet what effect this fish will have on our marine ecosystems but in places like Pearl Harbor or Kane`ohe Bay it is sometimes caught in nets intended for the the Hawaiian Anchovy, or nehu, a valuable baitfish, and may be preying upon them. (At other Pacific Islands, such as Fanning and Nauru, the picture is more clear: introduction of tilapias into saltwater ponds has damaged or destroyed traditional culture of mullets and milkfish and eradication has proved impossible.) In Hawai`i these fish are now considered pests in canals and reservoirs because they reproduce quickly, out-compete other species, and then often suffer massive die-offs. In 1991, for example, an estimated 20,000 tilapia--most of them Blackchins--died of a fungal infection in Lake Wilson, O`ahu. These were estimated to represent half a percent or less of the total tilapia population in the reservoir. At present about 10 species of tilapias are believed to be established in Hawai`i, although rampant hybridization can make identification difficult and uncertain.
     If you live on a Hawaiian island other than O`ahu and have seen tilapia in pure seawater, please drop me a line. For more information about Tilapia in Hawai`i see "Hawaii's Native & Exotic Freshwater Animals" by Mike N. Yamamoto and Annette W. Tagawa.

Blackchin Tilapia - Queen's Beach, Waikiki, O`ahu. 3 ft.
Sarotherodon melanotheron Rüppell, 1852
These dull silvery or faintly yellowish fish are named for the black coloration often present under the chin. When breeding, males may become darker overall. These fish are mouthbrooders can sometimes be seen holding eggs or fry in their mouths (as the fish above may be doing). Originally from brackish estuaries and lagoons of west Africa from Mauritania to Angola, they were introduced to Hawai`i from New York in 1962 for possible use as a baitfish in the tuna fishery. After proving unsuitable, they escaped their holding tanks and spread quickly through the fresh and brackish waters of O`ahu. By the 1970s they were abundant in Lake Wilson in Wahiawa and various other O`ahu reservoirs, as well as in many lower streams and estuaries. Eventually they displaced the Mozambique Tilapia (Oreochromis mossambicus) as O`ahu's most common tilapia. Tolerant of high salinities that would quickly kill other freshwater fishes, they have penetrated protected coastal waters and now occur in such places as Pearl Harbor, Honolulu Harbor, the Ala Wai Canal, and along Waikiki Beach. Off beaches and open coasts they seem to be staying close to shore in waters less than about 6 ft. deep and have not invaded the deeper reefs. Most likely they cannot compete with true marine fish. Hopefully that will not change in the near future. On O`ahu, a good place to see "saltwater tilapia" is at the stone jetty between the Waikiki Aquarium and the Kapahulu Groin (Kapahulu Ave.) at the Diamond Head end of Waikiki, where you can easily spot them from shore swimming in small groups. To about 10 in. Widespread throughout the tropics and subtropics in fresh, brackish, and protected marine waters.

Blackchin Tilapia - Queen's Beach, Waikiki, O`ahu. 3 ft.


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  Text and photos copyright John P. Hoover