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Re: [Killietalk] RE: Role of vitamins in fish color

Point taken, Dave. I think the exceptional coloration and quality of fish raised outdoors, compared with large and fattened but duller fish raised in indoor tanks, intuitively must be a result of a wide variety of influences. Certainly sunlight's activation of vitamin D affects the health of many animals, and perhaps fish also (I don't know), and these miscellaneous health effects might play a contributing role in how intensively colored the fish appears. That color intensity could be the result of hormonally induced production or stimulation of secondary sexual characteristics that, together with pigments, enhance the fish's sexual attractiveness to other fishes. So too will the much better diet outdoors affect general health of fishes. Here they eat live (not merely fresh, live-stored/starved, live but raised on a restricted diet, or frozen) foods of myriad types, including a variety (not just one or two) of species of insects (exceptionally nutritious) in all stages of insect development (and with differing nutritional profiles). And there are also the annelids, nematodes, gastropods, crustaceans, etc., all in an array of life stages, with each type, species, and life stage having a different nutritional profile. Those profiles, BTW, are enhanced, and further diversified, by what those invertebrates have in their guts (what they were recently eating). In captivity, we are concerned with rapid growth to large size, fertility, and maximum survival. Anyone who has raised fish outdoors knows that you never raise a lot - instead you raise a smaller quantity of much higher quality fish. So there is also culling through competition, predation, and other mechanisms going on outdoors. Hatcheries operate differently from aquarists with outside pools. We dump fish out there with vegetation and hope for the best. Hatcheries feed heavily, change water continuously, and (pretty important) get their young off to a good kick start by practically immersing them in zooplankton as first food. We don't operate that way. So trying to find a single reason why outdoor fish look so good is chasing rainbows. The total environment is different, and so are the final fish. Remember, phenotype is the genotype as expressed in a particular environment.



----- Original Message ----- From: "Koran, David HQ02" <David_Koran at hq02.usace.army.mil>
To: <killietalk at aka_org>
Sent: Thursday, July 07, 2005 10:13 AM
Subject: [Killietalk] RE: Role of vitamins in fish color


Bob,

A couple of clicks did lead me to a melanin reference. I am not saying that
vitamins create the colors but probably are more related to the vividness of
the colors, enhancing pigmentation if that is possible. Most killies have
the expected color patterns but "conditioning" provides one with better
specimens. I would say that sunlight (and hence something akin to vitamins)
has a factor in all of this, however, is this primary or something that
hasn't received much study. I don't see a market SPF 15 creams for fish but
tanning beds, maybe...

From: "Robert Goldstein" <rgoldstein at rjgaCarolina_com>
Subject: Re: [Killietalk] RE: Role of vitamins in fish color

I don't know of any relationship between vitamin (or provitamin) D and fish
colors. The pigments I know of are melanins, pterins, and carotenoids.
Guanine crystals polare light reflected off the deep melanin layers to
reflect blues and greens through the guanine crystals.

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