Blue Jack Dempsey

I don't think the colour is sex linked as it is in other fish and animals.
Blue male JD to normal female JD produced mix of normal males and females.
Didn't get chance to cross blue father to daughters.
Brother/sister matings produced mixed percentages of blues and normals. Fry
of this crossing were both sexes in both colours.
But since a true breeding strain of the blues hasn't hit the market yet, I
am leaning to the electric blue being a lethal gene if both parents are
electric blues.
Fish can be surgically sexed but it's rough on them. I sex the JD's by
physical shape and behaviour to start, followed by close examination of the
genital pore, then confirming when fry are produced.
I forget the formula, but believe the odds of getting a pair in 3 fish is
3-1 (successful in 75%), not 2-1. With 4 fish, I think it's 8-1 (Successful
in 87.5%).

Jim

bassett wrote in message
...
Could the Colour be sex linked,, Someone said that they will not breed
Blue to Blue
therefore could the Genes be linked by sex, Blue Dempsey "Male" Split to
Blue [ appearing as normal color] female. Therefore all the Blue Fry will
be male and all the normal color fry will be female..but split to "Blue"
The same gene applies to some breeds of Parrots i.e. Indian Ringnecks..
Breed male
yellow x green female [split or normal ] all the resulting chicks that are
yellow are male
all the green chicks, will be green split to yellow female, But in the
female the gene is recessive. This is a simplification of the genealogy,
once you get into mixing recessive strains it can get very compacted.
It is possible to surgically sex fish, ?? as with parrots. I realise
that
there are other factors to consider, namely fish are water breathers
sorry, but it is a consideration when you involve surgery] and there
would
be some difficulty with anaesthetic and surgery. I realise that surgical
sexing is possable with autopsy, but this would be counterproductive..
And
as most fish are dimorphic perhaps this situation has not come along
before,
Simple put three fish in a tank for a 2 to 1 chance of a pair, or 4 fish
for
a 3 to 1 chance and so on..

bassett