red pigment in zebrafish

christian lawrence clawrence at
Thu Mar 31 08:18:00 EST 2005


Thanks to everyone who responded to my query... a few general questions

I thought that the fish needed to have erythrophores to produce red/orange
color in the skin, and that zebrafish do not have these cells. If this is
the case, they wouldn't show red/orange coloration, regardless of the
levels of astaxanthin is provided in the diet.  Perhaps this isn't the
case.  Which cells express the pigment - xanthophores?  Or is what I am
really seeing a very intense yellow/gold, and not a true red/orange,
caused a by elevated carotenoids in the diet?

We used to feed our fish a diet augmented with cyclop-eeze (vibra-gro
pellets coated with cyclop-eeze and spirulina) as well, but never observed
any reddish orange pigmentation in the fish.  The males of most wt strains
were very yellow/gold; presumably the carotenoids in the diet enhanced
xanthophore production in the skin. Perhaps we were not getting enough
into the fish to see the orange/red effect.

We now feed a pellet feed from INVE, and coat it with spirulina.   Whether
or not this contains astaxanthin, I'm not sure, as it isn't listed in the
nutritional profile, but the pellet is a bright orange, similar to the
color of cyclop-eeze, so it must contain carotenoids of some nature.  I
know some cyprinids can convert lutein or carotene obtained from the diet
into astaxanthin; perhaps zebrafish can do this too with whatever
carotenoids are in the pellet and/or spirulina.

Whatever the mechanism, I guess the more interesting questions are 1) why
it is manifested in some strains and not others, 2) why is it localized to
the anal fin, and 3) why is this predominantly seen in males and not

By the way, the strain in which we are seeing this is SJD.  I've seen one
or two fish in the AB background that show this, but it is every healthy
male in our current line of SJDs that show this most obviously.

Christian Lawrence
Brigham and Women's Hospital
Karp Family Research Laboratories 06-004B
One Blackfan Circle
Boston, Massachusetts 02115
Tel: 617.355.9041
Fax: 617.355.9064

-----Original Message-----
From: owner-zbrafish at
[mailto:owner-zbrafish at]On Behalf Of David Lains
Sent: Sunday, January 30, 2005 8:47 AM
To: zbrafish at
Subject: RE: red pigment in zebrafish


Hi Chris

Zebrafish can not produce red pigments on their own.  It needs to come
from the environment.

We feed freeze dried Cyclop-eeze to increase this red pigment in the
males. It's ~35,000 ppt astaxanthin which is also the red "color added"
ingredient they feed to farmed salmon.  It is a naturally occurring
pigment produced by certain algae.  It's also great for increasing
fecundity as it is loaded with fats and fatty acids.

There are other red pigments added to food but Astaxanthin seems to be the
most common.  It is sold as nutrarose which is a spray dried algae that is
very high in Astaxanthin.

The ability of zebrafish to express the red varies from line to line. Most
lines only the male express the red.  Some lines show little red in the
males and other show it in both sexes but this is a rarity rather than the

Best Fishes
David Lains <}}}><
Research Assistant
Zebrafish International Resource Center
5274 University of Oregon
Eugene, Or 97403

-----Original Message-----
From: owner-zbrafish at [mailto:owner-zbrafish at]
On Behalf Of clawrence at
Sent: Sunday, January 30, 2005 2:44 AM
To: zbrafish at
Subject: red pigment in zebrafish


Hi All,

Has anyone ever seen zebrafish with red pigment cells?  I've just noticed
that we have some fish with a noticeably orange-red tint to the anal fin,
different than anything I have ever seen in zebrafish.
Further, it is only present in males.

Anyone have any ideas?

Chris Lawrence




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