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Thread: Killifish inbreeding

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    Killifish inbreeding

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    Inbreeding is needed to create a pure strain of killifish. It could possibly happen in the normal killifish habitat, but probably not to the extent that it occurs in the aquarium hobby. I have read that some live in "small" puddles, but I still do not know how "small" it really is. I know many of you have been in the hobby for a long time, so has anyone experience any problems with this type of selective breeding?

    I ask this because I have not seen a single complaint of creating F2, F3, etc generations of killifish or even heard of problems arising because of inbreeding. Is there enough genetic variation to protect our fish from diseases or are we slowly making the generations weaker?
    -Mark Mendoza

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    Hi Mark,

    Regarding your question about inbreeding, yes it occurs from time to time, especially with populations that are kept only by a few people, or with populations that have been inbred for several generations without the addition of new fishes to add to the gene pool. Most breeders will use breeding groups of at least 6 or more fishes to ensure that the gene pool will be large enough to last the fish for at least several generations before new blood needs to be infused into the bloodlines.

    Most people start off with eggs that came from parent fish which were at least of F2 generation or even later down the generation ladder. It is highly likely that problems will arise much later or even sooner. Deformities such as bent backbones and maybe even belly-sliders or even stunted fish can be linked to genetic problems. Sterility of the fish is a major headache for any breeder and it does happen. Responsible breeders will always look for fish/eggs of the same population but from a different source or breeder to introduce new blood into their lines from time to time to ensure that such problems do not arise.
    Fish.. Simply Irresistable
    Back to Killies... slowly.

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    Re: Killifish inbreeding

    Quote Originally Posted by Slaigar
    I know many of you have been in the hobby for a long time, so has anyone experience any problems with this type of selective breeding?
    Actually, Mark, we haven't been in the hobby for very long. But this topic of inbreeding was once discussed. If you like to read what was said, click here.

    Loh K L

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    I have a question regarding inbreeding and breeding population.

    Often killifishes are tagged with collection code, and sometimes a locality label. Logically the collection code should translate to a collecting locality. Now if you are maintaining a population, would you add new specimens only with the same collection code, or would you add specimens that have same or nearby localities regardless collection codes?
    why I don't do garden hybrids and aquarium strains: natural species is a history of Nature, while hybrids are just the whims of Man.
    hexazona · crumenatum · Galleria Botanica

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    Choy, the serious Killifish breeders are particular about collection codes so they will never add specimens from other localities even if the localities are just a neighbouring pond or a stream close by. Once 2 fish of different collection codes are interbred, the offspring becomes aquarium strain. Some Killifish breeders think aquarium strain fish have no value.

    Loh K L

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    Actually in my humble opinion, and even humbler understanding of genetics, is that fishes from the same or nearby locality should be considered a breeding population. If we impose collection code constraints, even though the specimens could be from the same area sampled some years apart, we're simply artificially reducing gene pool diversity. Is there any good articles or papers explaining why it is inappropriate to mix specimens provided we can establish that the physical collecting localities are the same?

    please ignore the fact that I hardly keep any killifishes, not to mention breeding them :wink:
    why I don't do garden hybrids and aquarium strains: natural species is a history of Nature, while hybrids are just the whims of Man.
    hexazona · crumenatum · Galleria Botanica

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    Staying with the exact location for selecting breeding pairs is probably to avoid any genetic deviation. Even if they are the same species but from different locations, breeding them may be associated with "hybridization"(maybe not the best term), and the phenotypes are no longer "pure" with the creation of fish of a new colour. This is probably to satisfy ourselves aesthetically rather than ensure the adaptability of the species.

    Thank you, Mr. Loh, for that thread. What caught my eye in one of the posts was by Eric:
    Quote Originally Posted by woodduck
    There a strange thought from me, the Nothobranchius may have look different 100 years back.
    If the fish vary in colour as geography and habitats change, they may be introduced to other varieties of the same species.
    -Mark Mendoza

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    Let's say a wild bird caught a species of killfish from location A & somehow drop it at location B, which the same species are found, but with different location code, then a new strain is formed ?

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    Quote Originally Posted by turaco
    Let's say a wild bird caught a species of killfish from location A & somehow drop it at location B, which the same species are found, but with different location code, then a new strain is formed ?
    Location/Collection codes were introduced into Killifish names because the people who collected the fish weren't sure of their identities. The codes do not necessarily mean the fish are of different species but it ensures that if they are, they can be traced back to the ponds/streams where they are found. Identification of species is a tricky thing which is best left to experts so the collectors were right to do that.

    In nature, species rarely interbreed. Even if they do, the offspring rarely survives because any individual that is different from the general population is more likely to be eaten. For instance, there are no albino Tigers in the wild because with that kind of skin colour, there's no way a white Tiger can camouflage itself effectively. Albino Tigers exist only in zoos and places where they are selectively bred in capitivity.

    So the answer to Gan's question is - If they were of the same species, the question of a new strain occuring would be irrelevant. If they were of different species, chances of a new strain would be very slim because hybridisation rarely occurs in nature.

    Loh K L

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