Nenue are a large, gray, schooling fish that are generally known as chubs. There are several common species here in Hawai‘i that are often seen in large schools called gray chubs, highfin, brassy and bicolor chubs. These common, shallow-water fish can grow to about 20 inches long and are often seen right up close to shore where the feed of marine plants. They zoom back and fourth with the surge from the waves, and sometimes a snorkeler will get surrounded by over 100 nenue in a single, large, fast-moving school.
During breeding season the male chubs will often develop a spotted, black-and-white pattern, but from time to time divers see a bright yellow nenue.
It is truly a beautiful fish, and I have only seen five of them in all of my diving throughout the Hawaiian Islands. In old Hawai‘i the rare yellow chub was called the “queen nenue,” and was thought to be a very special fish.
Nenue are good to eat, and have been a sustainable food source for over 1,000 years for the Hawaiian people. They are often speared in shallow water or caught by throwing nets, but if the queen nenue was caught by accident it was immediately released. It was thought that the gray chubs would follow the queen and a fishermen could develop a good relationship with the local queen and she would lead fish into his net.
The yellow color of the queen nenue is caused by a genetic defect. The gray colors of the chub are created by black pigment in the skin that lays on top of a layer of yellow pigment. Two different genes control these colors, as is very common with fish and reptile species. Sometimes the black color is missing due to a genetic defect in the fish colony. The condition when the black color pigment is missing is called “amelanistic.” What is unusual about this uncommon color variation is the yellow fish still has black eyes.
Amelanistic fish and reptiles tend to die in the wild, as they are so brightly colored that get picked off by predators. But in captivity it is fairly easy to captive-breed these animals and produce an entire colony of bright yellow fish or reptiles.
Since their color pattern is controlled by just two genes you can take a yellow adult male and breed it with a normal gray female. All of the offspring will be gray, but they carry the gene for being amelanistic. If you then breed the yellow adult to one of his gray offspring the next generation will have 50% yellow babies. If you raise up the yellow babies and breed them together 100% of their offspring are yellow. This is how the now-famous albino Burmese python was produced that you often see for sale in pet stores on the mainland.
The queen nenue is not an albino as sometimes thought, because a true albino will lack all color and would be pure white with pink eyes. Sometimes there are nenue that are part yellow and part gray. This is another genetic variation we call “piebald,” and it is governed by a set of more-complicated genetics then the amelanistic color pattern.
Amelanistic color patterns in fish and reptiles are simply the lack of the black color controlling gene or genes, so the animals’ color is just what underlying color pattern is left.
So why do a few of these rare yellow nenue survive in the Hawaiian population? They do not seem to have any different feeding or behavior patterns then the regular gray chub, and I know they can live for quite a long time. I have seen a queen nenue at Tunnels Reef (Makua) in Kaua‘i now for over five years, and one along Napali Coast at Nualolo for over eight years.
You can see the yellow nenue in action in the video “The World’s Guide to Hawai‘i Reef Fish” on the marine life educational web page at www.underwater2web.com, and if you see one of these cool-looking fish where you live please let me know on my Facebook under my name Terry Lilley or Instagram at terry.lilley, as I am trying to find out if they occur on all of the Hawaiian Islands and also through out the Pacific Ocean.
Please stay tuned for a new Online Marine Educational Series expected to launch soon for all of the school kids that are having to stay home due to the coronavirus outbreaks we are currently having. I have enough online marine-life videos to keep the kids busy for years, and they are fun and educational for the parents to watch, too.
Aloha from under the surf.
Terry Lilley, a marine biologist, lives in Hanalei. His websites include underwater-2web.com and gofundme.com/5urrm4zw.