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RE: Fish Quality

> Alfred Heng <alheng at pacific_net.sg> wrote:
	> Can the quality of a fish be improved with proper care?  I
bought some
> > really sad looking cherry barbsand zebra danios 6 months ago (real
> cheap
> > and I meant to use they to cycle a tank), but with good water and
> food,
> > they now look really good now and I am wondering if this would hold
> true
> > for most fish.  
Absolutely.  Given any good environment (food, clean 
water, etc.), fish will tend to grow larger, pick up more
color, and show an increased resistence to disease or
other stresses.  The same is true for plants.  Some may
argue the same is true for our kids.  ;-))

	> Will the color improve with proper care.  Will the
> > offspring if bred, be better then the parents?
The color will improve with environment, until
limited by genetics.  Overly inbred fish, for
example, tend to have more subdued colors than
their wild-caught brethren.  The offspring in a good
environment do not suffer the earlier environment
given to the parents, and will likewise not be

However, we are mixing environmental fitness and 
adaptation with genetics.  Be careful.

The genetics of poorly treated siblings with well-treated
siblings are very similar.  However, the well-treated fish
will tend to be larger with more color, and have a greater
likelihood of high-percentage breeding success.   For
example, the well-treated fish will be more likely to
breed (some exceptions), will more likely be larger
and have more eggs, and the eggs will more likely be
larger with a resulting increased resistence to
environmental stress.  The fry will likely be larger, and
thus have a "head start" over other fry hatching at
the same time from a less well-fed parent.

The resulting genetics of the offspring from
well-treated or poorly-treated parents will be similar.  
If both are given a good environment, theoretically the
grandchildren will have the same capability for eventual
size and color.  The reality is that yes, there are
some thresholds that may impair children from
healthy parents over children from unhealth parents:  
temperature, size, environmental conditions, availability 
of live food, etc. have all been shown to cause changes
in fish morphology (e.g., birth defects and growth
defects), the maturing process (dwarfism), and
even sex determination.

The archives talk about environmental response
mechanisms, relating to genetics and individual
adaptation.  If your fish responded to your better
tank environment, and if you chose to breed them
(or it happens anyway), then it won't matter if they
started with a hard life as long as they actually 
reach mature size, or are still capable of reaching
mature size.  (There is a window of time that won't
matter, and a window of time where the individual
can never catch up).

charleyb at cytomation_com