Hi Renate,
Yes, certain color morphs of Angelfish can only be developed tp display their genetic make up when reared in specific durations of light. Joanne Norton had written of both Half-Blacks and Leopard Angels as needing only certain periods of light per day, or they would develop as appearing to be Silver Angels even though they had the genetic make up of these other varieties. There may be other Angelfish strains she mentioned which require only a certain amount of light, but as it's been a while since I last read the late Dr. Joanne Norton, I don't quite recall at this time.
There's a chapter (Fish Genetics) in the book, "Aquariology (Master Volume) -- The Science of Fish Health Management" by Dr. John B. Gratzek, which I have, in which Joanne Norton had explained this in detail. I recommended this book on at least several occasions on the other Yahoo group many of us are on. The book is long out of print (1992) but there's a good chance a copy can be found on eBay, just as many other publications can be found. I believe that this master book was also offered as four smaller books, covering parts of the master book. If this were the case, I'd guess that the Fish Genetics Chapter should be found in the Aquariology issue as "Anatomy, Genetics, and Breeding" if the sections of the larger book are any indication of the smaller book's titles.
Light does play an important part of the color formation in most fishes, even though that coloring may only be temporary in some situations. Early on in the hobby, before black vinyl liners were used for building ponds, it was recommended that the pond keeper paint his pond a darker color rather than having it too light; many ponds those days were made of poured cement and needed to be painted. Some of those earlier pondkeepers would also sink bathtubs in their yard and if left unpainted, could result in bleached-out appearing fish when they were brought back indoors. It's tough to sell one's excess fish to stores when they don't even have near the normal intensity of colors that they should otherwise have. Fish are affected by, and take on the tone of the bottom of their environment as a way to blend it with it, so they're not an easy target for predation.
I remember many years ago, when I set up several display/educational tanks at one of my club's annual shows. Besides setting up an Angelfish display tank (of course!), I also set up an Oscar display tank. For the substrate, I used black gravel generously sprinkled with red gravel. When I first put the Oscars in the tank, they were moderately dark, as Oscars are naturally a somewhat dark colored fish -- with mostly a red pattern overlaying this base color. At the end of this week-long show, these fish were virtually black with vivid red markings and looked spectacular. These fish were not in competition, but were only there for educational purposes for the public, so it wasn't as though I was doing anything unfair to gain an advantage. As it turned out, I really didn't need to stoop to any unfair methods, as the pair of Oscars that I did enter into the show (without any gravel) not only bred at the show but took the Best in Show award. Those days (45 years ago) all entrants (except for large catfish and oddballs) needed to be shown in pairs. Those days too, the shows were a week long, not one or two days as they are now. Anyway, this demonstrated how fish can take on the color of their environment's bottom.
Dawn brings out other influences of color on fishes, the color of the light bulbs and food -- especially natural food. This is where fish put out in the pond for the Summer not only will grow to a large size fast, but will color up very brightly from the nutrients they get from insects, etc. The vitamin D she mentions is a great benefit for the fish in helping develop color, not only coming from the foods but from natural sunlight. Fish can be induced to greatly intensify their natural colors just by feeding them certain foods containing Beta Carotene. These would include shrimp, krill, lobster, crab and many other foods containing this nutrient -- and is why, in the past on these groups, I've recommended including frozen Mysis Shrimp in their diets whenever possible.
Ray
--- In tropicalfishclub@yahoogroups.com, "haecklers" <haecklers@...> wrote:
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> I was reading with interest last night the writings of Dr. Joanne Norton about how to get different color patterns in angelfish by raising them in darkness or only 4 or 8 hours of light, or constant light.
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> Some kinds of crayfish will become blue when raised in darkness.
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> Are there other kinds of fish that have different color patterns depending on the amount of light they are raised in?
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> I've heard that some gouramis get a lot more vivid colors when they are in sunlight (outdoors) and I've seen myself that bettas get richer colors when they are kept outdoors in the sun. Guppies also get some color enhancement from being outdoors, and they get a lot more active and alert.
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