Mutations and breeding healthy fish

Hey folks, here's a question for you all...

Now that I've got all of these new fish (mostly Tangs), I was wondering how often pepople introduce fresh genes to the pool when breeding their fish. My Mbunas were fairly successful and I felt that I had low mutation rates from them, but I was assuming a lot of that was beginner's luck.

But then I started thinking...I got most of my mbunas at the same time, took them home, threw them into the tank together, and eventually they started breeding. But since I got them all at the same time, the fish were most likely already siblings.

What have your experiences been, and what do you do to make sure you're not creating more problems by too much inbreeding?

We try to get the same fish from at least 2 different sources, even if it's people we know in the club. Like if we're getting a group of 6, we'll get three from one source and three from another

Low mutation rates?

I probably shouldn't even touch this, but just out of curiosity, whom here has observed "mutations" in their tanks from inbreeding? No question it's good to mix up stock from different sources, but fish are less prone to negative effects from 'inbreeding' per se than so-called higher animals. I inherited some Endlers that are from a 15-year old captive line and they seem to be just as robust as wild caught. As for Rift Lake species, their entire history and speciation is one of inbreeding. There's some natural mutation and hence genetic variation within broods and lines that is generated naturally even among siblings, am guessing you'd have to be a pretty successful breeder over a bit of time or be doing line breeding to run into problems with 'mutant' fish. Be very surprised if mixing in a few individuals from a different source every few years or half-dozen generations wouldn't be sufficient to keep a line healthy.

Admittedly fair amount of qualified conjecture here, be interested to hear from someone(s) with qualified experience 'cause I'm just not there yet.

With my Mainganos, out of about 100 fry across 3 broods, there was only one fish where I noticed physical deformity. I did see color variation, but nothing I'd say was negative. So, is 1% good or bad for Mainganos?

If someone were serious about a breeding program for Mbuna I would guess that 5-10% would be pulled and culled for some type of deformity, and that 1/3 would be pulled and culled for other reasons, ie lack of color, size etc.

Avatar said:

Far far likelier that deformity is a result of hardware issues (post fertilization/physical development problems in or to the zygote) rather than problems with the software (DNA), particularly so if it's a low rate of incidence.

Since William has a very critical and unforgiving eye, perhaps he can tell us if the 5-10-% cull rate applies equally to broods from wild and established captive lines.

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S.L.
Since all of the Mbuna I have ever bred, to the best of my knowledge (which isn't saying much), have been tank-raised I cannot give an answer.
I have, however, found that I cull about 1 out of every 30 Tropheus that I have bred for deformities...and this is both tank-raised and Wild Caught.

I haven't personally observed genetic mutations in our lines, but here is an article on someone who has in Angelfish.

http://www.theangelfishsociety.org/articles/norton/dr_norton(18N).html

Genetic mutation is VERY possible, although rare, and is also where all those "cool colored" Angelfish come from. The colors are genetic mutations not found in wild species....

Genetic mutation does occur but it's difficult to identify unless you are breeding the same line over and over again. Deformities can be caused for a lot of reasons (snub nose, curved spines, missing caudals, etc...) that are not genetic and these fish should be culled.

One genetic mutation that is caused by aquarists is shrinking of the fish. Many commercial breeders and hobbyists breed their fish at a young age and don't select for the largest parents as would happen in the wild. Over time this causes the aquarium strain fish to shrink in size. Introducing wild stock genes into the pool periodically can mitigate this trend.

There was a good talk about this issue with swordtails I saw a while back. I can't remember who did it.

Andy

The issue of genetic deformities occurring as a result of captive inbreeding is (in my opinion and experience) WAY overblown.

The quality (meaning the level of deformities, aesthetically desirable color, desirable shape, etc.) of stock is much more important than the genetic diversity of it.

In other words, (unless the goal of your breeding is to accentuate some abnormal / aberrant characteristic(s) as in electric blue dempseys or long-fin or veil whatevers or balloon rams, etc.), simply excluding abnormal fish from breeding will go a long way to ensure that your line remains healthy.

As Sam noted, many mbuna (and other fish) are naturally highly inbred (i.e. from relatively small populations that are geographically isolated from a wider gene pool).

As an aside, I wonder what (decades) of (un-natural) selection of the most aesthetically pleasing individuals from particular collecting locations has done to the genetic diversity of those populations?

Long answer short: Christine, don't worry about introducing outside lines...just don't breed any that are deformed / abnormal. You don't need to cull them, but I do (via feeding them to bigger fish)...

Matt

A lot depends where the fish is from and what type of fish.

When I bred mbuna many years ago... this was rarely an issue. With new world cichlids this is even less of an issue as they are more genetically diverse.

Water conditions can also be an issue with deformities.

I know with sand sifters from lake tang... their genetic make up is limited and diversity is a must. IME a lot of lake tang fish need diversity. I try with most groups I have to get them from at least two sources. Sometimes three or four if I am dealing with TR fish.

Sarah, for Tangs how often do you re-introduce new fish? Every few years?

AndyNarwhal said:

One genetic mutation that is caused by aquarists is shrinking of the fish. Many commercial breeders and hobbyists breed their fish at a young age and don't select for the largest parents as would happen in the wild. Over time this causes the aquarium strain fish to shrink in size. Introducing wild stock genes into the pool periodically can mitigate this trend.

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Yeah, this definitely occurs. The first male to breed is not always the best specimen as an adult.

It's not introducing every year per say....

What I typically do is buy the groups either as wild or TR and have them live together from the start. If I lose any fish along the way I would bring in new ones from a different source. But in general when I start a new group of fish I do it from the beginning so they get along better.

When fish breed I generally do not raise the fish up to breed them back. If the groups get too small I simply sell the adults as I do not like to breed the fish back to each other. Yes, it can be done but I personally do not like to do it for the mere fact that people tend to breed my fish and problems that are out of my control can happen down the line in other peoples tanks.

Even if fish are from two different sources can be very closely related. Although it's an extreme example, for many, many years ALL of the yellow labs in the hobby were from a small group of wild fish. I'd blame the decline of "quality" of yellow labs more on poor breeding practices (i.e. breeding atypical fish, hybridization along the way, etc.) than on inherent problems from inbreeding.

And you're correct that poor husbandry and un-natural water (i.e. water different than native habitats) result in a lot of the deformities and abnormalities seen in aquarium bred fish (bent mouths, sex skewing, stunting, deformed backs, etc.)

There is risk involved in introducing "new blood" into a breeding line...and this risk needs to be weighed against the (in my opinion overblown) risk associated with inbreeding. That a fish - even a "wild" one - is what it's supposed to be can be highly uncertain. I only trust that (especially "wild") peacock females are properly identified when I see that their offspring look OK. Especially with commercially sourced fish, there are way too many hand-offs and opportunities for confusion between the source (lake) and the purchaser for there to be complete certainty. And that's assuming that "wild" fish are actually wild (i.e. from a locale in the wild).

(Some) New World fish are every bit as inherently genetically concentrated as rift lake species. It's the nature of cichlids and their adaption to rapidly evolve to their habitats.

The only widely available Australoheros (chanchito) in the hobby is A. n. sp. "Red Ceibal", which is only found in this little stream in Centurion, Uruguay.: http://cichlaholic.com/uruguay_list.html#redceibal

It's a pretty fish, so it's been farmed...and widely sold...but all of the stock came from this one location... And the chanchitos from this spot in Centurion are slightly different than the ones in the pond down the way....because this small population of fish has (rapidly) adapated to the particular conditions in that stream. And the only "new blood" that could possibly arrive in the stream could (possibly) be from a big storm / flood...or from human intervention. Either of which would fundamentally change the nature of "Red Ceibal" chanchitos.

Even more extreme example, is the chanchito found in Canada El Sauce, which is a little pond where we collected in NE Uruguay. It is literally a pond, probably 1-2 acres in size...probably sourced by an underwater spring. The fish in it - chanchitos, gymnogeos, pikes, livebearers, etc. - probably found there way there (who knows when) after a flood...and then were isolated...and began to evolve to the conditions of THAT pond. The chanchitos there are DIFFERENT than any other place...including the chanchitos from the relatively close rivers and streams...and I'd assume highly inbred...

http://www.monsterfishkeepers.com/f...-Canada-El-Sauce-quot&highlight=Australoheros

Sorry to ramble

Matt

longstocking said:

A lot depends where the fish is from and what type of fish.

When I bred mbuna many years ago... this was rarely an issue. With new world cichlids this is even less of an issue as they are more genetically diverse.

Water conditions can also be an issue with deformities.

I know with sand sifters from lake tang... their genetic make up is limited and diversity is a must. IME a lot of lake tang fish need diversity. I try with most groups I have to get them from at least two sources. Sometimes three or four if I am dealing with TR fish.

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I was talking generally Of course their are exceptions.

The hobby is a very small world. So if you do introduce new blood make sure it really is new blood. Many of the more rare fish are from one or two lines in the hobby.... try and trace the fish back to who brought them into the states.

Yes damage can be done by "bringing in new blood" .... but damage can also be done by not doing this. I typically start with a group of F1 and/or Wilds.... then work from their trying to find new blood. Also try and work with the largest gene pool you can afford. In other words... don't buy one female and try to do this. By 6 or more each time and the gene pool shouldn't be affected in a bad way. When dealing with wilds ... and TR it's not as much of a worry... it's when you are breeding TR to TR bad deformities tend to pop up more often. It's easier to start with wilds or F1...

longstocking said:

I was talking generally Of course their are exceptions.

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I think it might be fair to say that speaking "generally" there's very little need for introducing 'new blood', and that the "exceptions" are the type of precautions you describe taking for sand-sifters. For most cases/species, unless you're trying really hard to isolate and compound expression of specific genes, or have a species that's already compromised as you suggest, seems inbreeding is unlikely to ever be a problem.

Sam... while most cichlid I would agree with you on... lake tang fish tend to have more problems in this area. Sand sifters are the worst in lake tang but most of them by the 3rd or 4th generation need new blood. Maybe I am overly picky... but, it is just what I have noticed.

I definitely agree with large harems (where appropriate) - some opportunity for natural selection of traits among the harem, especially if there are multiple males. While fishkeepers might value the largest, most colorful specimens, Mother Nature doesn't always!

This opportunity for genetic diversity simply isn't possible with pair-bonded fish.

I'd like to know more about why featherfins specifically need to be outcrossed after only a limited number of generations of inbreeding.

I'd assume that - like mbuna, haps, peacocks and other rift lake species - that the various varients have limited populations / genetic diversity in the wild. Could environmental factors (e.g. sensitivity to organics) or something else be at fault for higher levels of deformities (vs. genetic reasons)? How many people have bred 4-5 generations of featherfins, anyway ?

Matt

Never said otherwise...

longstocking said:

Sam... while most cichlid I would agree with you on... lake tang fish tend to have more problems in this area. Sand sifters are the worst in lake tang but most of them by the 3rd or 4th generation need new blood. Maybe I am overly picky... but, it is just what I have noticed.

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...and who would I be if I refused deference to one so accomplished and far more experienced than myself? Needn't answer that - strictly hypothetical. It is as I first posted - always interested in hearing from someone in possession of "qualified experience", especially when it is at variance with my "qualified conjecture" (as in smoke issuing from the general vicinity of my backside).