I'll offer my POV on a couple of points you raised below.
Regards,
Bruce.
Bruce Hansen, ANGFA, caring for our aquatic ecosystems.
Please visit us at http://www.ozemail.com.au/~fisher/angfa.htm
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> From: Georgia Mountain Web <juliesis at ellijay.com>
> To: rainbowfish at pcug.org.au
> Subject: Re: [RML] Water quality & hybrid
> Date: Saturday, 31 January 1998 20:48
>
-------->
>
> Talking about crossing fish, etc, I know nothing about this but am
pleased
> to see that my neons are in with other rainbows and they have remained
> paired off - they have no interest but in breeding with each other.
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hybridising is more likely to occur if available mates of the same species
are not available, or if the available mates are not sufficiently well
conditioned.
In nature there is usually sufficient choice, appropriate locations and
other factors favouring each species spawning pattern (including displays
etc that make each female decide whether she will accept his advances)
If his "moves are unwelcomw for whatever reason then she usually has
sufficient space, cover etc to avoid his attention and he in turn can
cruise around and seek an alternative that may be more receptive.
Things like upper or lower levels, favoured time of day, colour of nuchal
stripe, shade or sun, nearness to plants, depth of water and so on have
gradually been incorporated into their genetic "screenplay" and as I
understand it these things are a large factor in why natural hybrids occur
so rarely in the wild.
> I know for rainbows this is probably not the case, but is overbreeding
> occuring in aquaria so that the resulting fish have poor traits? I once
> wrote a reference guide for a breeders club and I was saddened at some of
> the negative traits that appear over too much breeding, i.e., the
bronchial
> problems of some bulldogs, hyperactivity and agression in some breeds,
etc.
>
> My dog is a terrier-sheltie mix and is a wonderfully calm and loving dog.
> My vet said that mixed breed dogs and cats often make the happiest and
most
> healthy pets.
>
> How does or does any of this at all relate to aquaria?
The problem with human controlled breeding of any organism is probably that
to most intents and purposes we tend to breed for "phenotype" or what it
looks like and for many animals especially as in the example of dogs that
you quoted the vast majority of important things like constitution,
temperament, fertility etc etc get ignored as long as it looks like the
man-made "standard" that has been drawn up for that breed. Many mixed breed
dogs have the desirable aspects of both parents but some also have the
undesirable characteristics too ;-(
If we are to seriously breed aquarium fish and especially since as Cary has
pointed out, access to more genetic material (and therefore more genetic
diversity) is often extremely limited we should breed from groups whenever
possible and perhaps with sexes as even in numbers as possible and continue
to breed from our oldest generation as long as we can to reduce the
escalating loss of genetic diversity that tends to occur at each
generation.