line breeding and out crossing!

I have a bit of a situation,
I have 6 angelfish, 3 Peruvians wild caught
2 Santa Isabel sp and a blue angel,
I'm not to keen on line breeding simply because to my understanding you breed brother and sister or father to daughter,
And apparently there can be health issues!
So that leaves out crossing!
Is it a fish crime to out cross or would line breeding be a better option?

what were you hoping for as an outcome? are you hoping to try for certain strains or just experimenting?
for starters you won't realy get the peruvians to go without the correct conditions but considering their w/c you could chance your arm without having to worry about inbreeding.

Well I have the option of out crossing if either of what I have pair up!
But what would be the lesser of two evils so to speak?

I believe the biggest problem in in-breeding fish is that you do not know how far you are along the in-breeding line, i.e. if the parents of your fish are already related or not, unless you procured your fish from two different (and maybe geographically distant) sources. And, as john says, the further down the line you are from unrelated parents the more chances you have of problems with the brood. I'm not specifically familiar with the genetic alteration you get in angelfish, but it would be a risk.
If you want to breed the angels, why don't you swap one of them with someone that is in a similar situation, and probably got the fish from a different source?
I personally get attached to my fish and never-ever let them go - I have to figure out what to do with a million or so youngster that I have (endlers, platies, white clouds minnows...), but I will have your same problem with angelfish, having two youngs got from same source and surely hope that both are the same sex.....

I'm not too sure what the final aim is.

Forget the Blue Angel if you plan on breeding.

Really, line-breeding would not really be a term I'd use for wild caught specimens showing the dominant genotype. ie not really applicable to normal wild-types.
It would be more used to specifically select a recessive genotype or specific mutation to increase the frequency of that genotype.

Well planned line-breeding does not necessarily lead to poor quality stock; it is poor selection of parents that leads to poor offspring.

Yes, line-breeding is a very long and involved process of back-breeding to parents and grand-parents and intercrossing 'cousins'/'aunties' etc.

In-breeding does not in itself cause mutations or poor health. Crossing brother and sister in itself does not cause problems.

Where in-breeding causes problems is where there is a recessive mutant genotype that may be concentrated in the offspring. In-breeding does not cause the mutation.
But, that can be overcome by simply selecting the right fish and observing the ratios of the offspring to work out if there is a potential problem down the line.

Geographical variations or other morphotypes in the wild may inter-breed quite readily, but on the whole it is advisable to keep variations to breeding within their own variation.

I recon that, apart from the blue angel, a cross between the other 2 would produce good enough fish; but breeding peruvian to peruvian etc would be a much better option as that would please all concerned (and would also be in favour with purists )

If the offspring show undesirable deformities then simply don't carry on breeding them.

In my opinion, I don't see a need for new mutant forms of angels.

ian

there is a way of inbreeding that i read somewhere before that does APPARENTLY repair certain abnormalities in angelfish but i can't remember so won't elaborate apart from saying this info is available on the net if you search different keywords you'll find it... also i don't agree in the diminished quality your blue angel maybe which is also a colour and strain being used to create certain strains... again info is on the net.
if you cross breed and want to correctly identify your outcomes and possibilities then a knowledge of genetics is a must, i looked into it but haven't gone about it yet because angelfish are my sons thing and was doing it with him.
personaly i'd say keep them true unless your not to bothered about selling because otherwise i'm sure they'll break your heart.... also not much point in cross breeding unless ye have an idea of what your doing and your result.

If an abnormality is the result of a positive acting or destructive allele then it would be possible to out-breed that allele if you have a heterozygous genotype for the gene by carefully selecting the offspring from within the strain.

But if the phenotype is due a defective or non-coding allele in a homozygous genotype then the only way to breed that out is by crossing with a different strain not showing the phenotype for a trait.

In some cases the genetics are not simple Mendelian genetics (especially where a phenotype is due to multiple genes or linked genes) then you'd need to calculate that relative distances between the genes on the chromosomes in order to work out the outcome.

In the early days of fish crosses, many of the people working on the breeding were not only fish keepers but were also geneticists. From that group we got loads of good strains, but in recent years there has been a miss-mash of crosses with the result of having some pretty awful mutts on the market.

When I started crosses siamese fighters about 40 years, my 'tutor' was Myron Gordon......the author of the only book on Bettas worth having and it was jammed packed with advanced genetics. !!

ian

In viable fish undesirable recessive genes weather they carry a desirable or an undesirable trait, are always masked by a dominant gene. Through inbreeding a recessive gene can be passed from both the parents creating a recessive offspring that will show the mentioned trait (homozygous state). Inbreeding does not create -of course- undesirable genes but it increases the chance that traits which are already present in a heterozygous state - and thus masked - will be displayed. The resulting off-springs will likely pass these genes to the next generation: inbreeding significantly increases the appearance (unmasking) of an undesirable/desirable trait (homozygosity).

When an undesirable trait shows up, it is possible to get rid of it by strictly controlling which specimens are used for breeding. Expert line-breeding will concentrates the desirable, and remove the undesirable genes in that specific line. Once the undesirable recessive gene is removed it cannot affect that particular line. Under the same circumstances, if the line is - instead - out-crossed, the phenotypic expression (the traits that are physically observable in an individual) of the gene will be masked, but the gene itself will be still carried in a heterozygous recessive state and resurface now and again.

In other words, unless you are prepared to keep breeding and culling, you'll end up significantly weakening your angelfish line.

IMHO for the purpose of a more 'casual breeder' as I am (and I believe many - if not most - fishkeepers) it is far more productive, fun, easy, less sad, and more ethical try to keep inbreeding to a minimum, thus keeping the lines stronger with more genetic variability within the specifics of a certain specie.

fishmama wrote:

In viable fish undesirable recessive genes weather they carry a desirable or an undesirable trait, are always masked by a dominant gene.

That is not really strictly true.
There can be overdominance caused by the heterozygous genotype....the recessive allele being that that produces the overdominance, and the phenotype seen is that of the recessive allele.

That is also not including the many cases of co-dominance etc seen in fish genetics.

Admittedly, this is getting into biochemistry a bit but, then again, ultimately the fish takes notes of its biochemistry.

ian

You are right... my apologies, never say never (or always - so it is) in biology, it should have been stated: 'In viable fish recessive genes whether they carry a desirable or an undesirable trait, are masked by a dominant gene, following a Mendelian type genetics.'

May be a mostly or often could have been a better choice for the purpouse of this thread, but you are right, and of course (without going into the details of Fisher vs Wright debate) the fitness overdominance and heterozygous advantage for Triosephosphate isomerase null alleles described among othes by Markus Ralser et al. (PlosOne, Dec. 2006 - TriosePhosphate Isomerase Deficiency Is Caused by Altered Dimerization Not Catalytic Inactivity of the Mutant Enzymes) should be also applicable to fish ...

sorry could not resist

Thanks for all the input lads,
Its still early days yet before anything pairs up,
My ratio of males and females have yet to be determined,
So il just have to wait and see what happens.
Thanks again!

@Angelcichlid.....keep us up to speed on this.

@fishmama.......it's good to have a good chat on this. In the reptile world I am seeing some rubbish going with 'genetic' breeding without the fuller implications being considered such as breeding a colour morph that is a psycho.
As you say, never say never in biology. The point being that even if we us humans think the genetics get too complex, the poor old animal still has to live with it.

Sickle cell anaemia in Humans is also caused by a 'destructive' recessive gene product....but the selective pressure being proposed as balanced polymorphism.

I'm presently looking at the problems behind the platinum white Bettas where there is a close linkage of colouration (mainly the opaque genes) and really duff fins.
Now, what is also coming out of that is that there is also a tendency for what appears to be "tryptophan deficiency symptoms" observed in specimens demonstrating some of the co-dominant phenotypes for the basal colours and aggression (these few specimens also show increased aggression and an increased tendency to displaying genetic overdominance)
I have not determined the exact nature of this problem, but there is a linkage to colouration. So, the outcome is that I am working to out-breed these traits. Thus far, I've removed the trait of weak tail-fin bases though.

@fishmama....I take it from your writings that you know a bit about genetics (proper genetics that is as opposed to 'blue eye' vs 'brown eye' genes stuff )

ian

Will do Ian,
As far as the Peruvians are concerned, they were sold as "wild caught"
I have my doubts!
Even if they are,they were quite small when I got them,
And there the image of each other,
Chances are there siblings,
If they are brother and sister, and they breed if I allow it,
Would this be line breeding?

@ Angelfish: Inbreeding is the mating of related individuals that have one or more ancestors in common. Linebreeding is a form of inbreeding.

Dog breeders define:
- Inbreeding as breeding first-degree relatives: mother-son, father-daughter, brother-sister.
- Tightline breeding as half-brother-half-sister, cousins,
aunt-nephew, uncle-niece.
- Linebreeding as mating grandparent-grandchild, or more distant relatives that share a common ancestor.
- Outcrossing as the breeding of dogs with no common ancestors, usually within a five generation pedigree.

I believe this is the same for fish (I don't know thou if they have the tighline breeding distinction and of course but unfortunately there is no pedigree).

So in your case if they are siblings you should properly call it inbreeding.


@igmillichip: I'm not geneticist, I did work in biology field thou... loooong time ago, something stucked with me, but mostly I'm faking my way around.. anyway I love to have this chats ) I was on holidays and had some time to fool around with internet and forums... so i was particularly active in this last few days, I should make an effort to keep it up.

What you say about reptiles is even more evident in dogs, unfortunately. I'd love to have the space and resources (and time so it is) to start breeding dogs and bettas, may be one day!

Very interesting the connection tryptophan deficiency symptoms/color/aggression, were you able determined by phenotypic observation (scoliosis or other?) or also bioassay?

Is funny also that you mentioned Myron Gordon, is long time that I'm looking for a good book on bettas (I believe he has also some kind of series on the tropicals but I looked last nite and all his books seem out of print, considered now more like collectibles...), since when I fell in love with bettas, a few years ago, and with the 'Apache' strain in particular, love first sight.

I was looking looking for infos, and stumbled upon the site 'www.bettatalk.com', she has good infos, and it seems she knows what she's talking about, she also has beautiful fish, too bad she's out of the betta business now (she is the originator of the Apache strain, also she mentioned somewhere the same book if I remember correctly).

But now I figured out were to get my next bettas ) And, oh by the way, I'd love to see your set up.....

I'm with fishmama in that if you cross the peruvians and they are siblings then that is in-breeding.

Line-breeding would be a long process that would take anything upwards of 9 generations to get a 'pure' line (given the misgivings of the definition of 'pure'); it is not a one-off process.

I recently got some peruvians, and they have the hallmarks of being wild (as well as described as wild).

@fishmama......a bit of biology chat is always good; I would be more from the molecular side of genetics from a biochemical (especially in human toxicology, brain and gut function, and cancer) point of view rather than the classical side of genetics.

The phenotype that shows tryptophan-deficiency-like symptoms shows lordosis AND scoliosis. In normal dietary deficiency, these can be corrected but this case is not correctable via diet. I need to do some more work on this though.

My set-ups are manifold and here and there. I have some photos and videos on the forum of different things if you fancy taking a look.

ian

JohnH wrote:

IGM:

"The phenotype that shows tryptophan-deficiency-like symptoms shows lordosis AND scoliosis. In normal dietary deficiency, these can be corrected but this case is not correctable via diet. I need to do some more work on this though."

I couldn't have put it better myself.


John

I could have tidied it up a bit though, but I was eating my Madras Curry at the time: very few things interrupt my curry.