4: domestication & colour mutations

by Paul Veenvliet
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4: domestication & colour mutations

Post by illustrator » Fri Oct 03, 2008 4:26 am

Besides topics related to my aquarium, I like to post some discussion-pieces on convict cichlids. This is one of these.
juvie2.jpg
Wildtype convict cichlid. This particular fish carries the mutation for leucism, which is not visible in its appearance. the only way to know is by looking at it's ancestors or it's ofspring: in this case I know that it has a leucistic father. The "funny things" in the tail-fin-rays are healing damages: it was literally breaking fin rays when bitten by other convict cichlids.
Without doubt, convict cichlids are amongst the most domesticated cichlids. That is, there are aquarium strains that differ quite somewhat from their wild ancestors. Some differences are more obvious than others, for instance behaviour differences are usually only noticed with dedicated behavioural research. Very obvious are mutations. I know of the following (please feel free to add to this list ...):

Colour mutations:

Leucistic (trade names: “white”/”pink”/”albino”/”white Congo”): fish without melanin in the body, but with normally pigmented (black) pupils. Also the orange colour of females is normally present. Iike with wild-type fish, the amount of orange in females is variable; some strains appear to be selected for a maximum amount of orange. Even some males of these strains may show a very small bit of orange colouration.

Marble (trade name: "calico convict"): fish with an irregular pattern of dark grey patches on a white background. The pattern varies individually; some have only a few dark patches, others appear to be entirely blotched. The orange colouration of females is not affected: this mutation appears to affect only the distribution of melanin. This appears to be a recessive mutation that is inherited independently of the leucistic mutation.

Interrupted bars: there are many reasons why bars can be interrupted, but the Austrian population appears to have quite some individuals in which not only part of the Y-shaped bar is interrupted (which is characteristic of many wild populations), but also the bar immediately behind the Y-shaped one. Probably this (and other) more subtle mutation is often seen as “individual variation”. I didn’t do any breeding experiments with such fish: would be very interesting to see if my view is correct! I suspect that there are more mutations around that affect the normal barred-colour pattern ...
connie2.jpg
Young leucistic convict cichlid: the black(grey) colours are missing in the skin, but the pupil shows normal black colour (this means that it is not an albino: albino's have pale pupils)

Other mutations

Short bodied (trade name: “balloon”): the vertebral column is clearly shortened, resulting in a round body shape and in difficulties with swimming. In my view a mutation that should not be bred because of animal welfare considerations.

Long finned: the fish start out with normal fins, but as they grow the fins become proportionally longer. I have seen only few pictures of such convicts, so I do not know how long the fins get in later age. However, based on experience with long-finned mutations of other species I think that there are also animal welfare considerations here: long fins are more fragile and, because of a greater risk of injuries, there is a greater risk of infections. Also, normal swimming is affected.

Bent pectoral fins: this is a mutation which I observed in aquarium specimens from the Netherlands (the ones I kept in the past): the pectoral fins had a pronounced 90 degrees bend: the tips pointed downwards. Such fish are usually not recognised as mutations, but are culled as “deformed fish”. Convicts from a different strain (which I kept later) did not develop this deformity, even though I kept them in the same aquarium on the same food. I believe that this mutation inherits recessive as the parental fish were normal.

Mutilations:

Sadly, some people feel that they should “improve” fish like leucistic convicts by injecting a colourful dye. I can’t believe that this is healthy for the fish, but above all, it’s utterly unnecessary!

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It’s interesting to note that some cichlids are kept in aquaria for longer than convicts, but never gotten such an impressive range of mutations. The only ones that come close are Tilapia which are bred for consumption rather than or aquariums.
Personally I don’t feel the need to change fish: I like them best if they are most similar to their ancestors from nature. But as long as there are no clear animal welfare considerations, I don’t see why fish with some mutations should not be kept.
Last edited by illustrator on Wed Mar 18, 2009 12:07 pm, edited 8 times in total.

Bas Pels
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Re: 4: the domesticated cichlid

Post by Bas Pels » Fri Oct 03, 2008 5:35 am

illustrator wrote:
Personally I don’t feel the need to change fish: I like them best if they are most similar to their ancestors from nature. But as long as there are no clear animal welfare considerations, I don’t see why fish with some mutations should not be kept.
I think I can agree with that: If people like the mutations, AND the mutations are harmless from a welfare point of view, why bother

But if the mutations are harmfull we should do as much as we can to prevent breeding/ spreading them

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Re: 4: the domesticated cichlid

Post by illustrator » Tue Dec 16, 2008 11:24 am

On the page from AquaMojo there are photo's of what looks like a black-spotted form of convicts

http://www.aquamojo.com/Convicts.html

Would this be Amatitlania coatepeque or hybrids with this species, considering the Y-shaped 4th and 5th bar?

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Re: 4: the domesticated cichlid

Post by illustrator » Thu Jan 29, 2009 8:32 am

I like convict cichlids "as they are in the wild" and I feel that there is nothing that can be "improved" on wild type fish. I have this in mind when I select young fish for breeding. This means that I don't keep leucistic young (although I accept that some normal-looking ones carry the mutation). I also don't keep young which look "different" in other ways, like this one, which has a bent fin-ray in its dorsal fin:
juvie.jpg
Juvenile convict cichlid with bent fin ray: I don't know if this may have a genetic basis.

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Re: 4: the domesticated cichlid

Post by illustrator » Thu Jan 29, 2009 8:51 am

This particular fish shows several "problems", but this is actually easier to see in the living fish than on a photograph.
out.jpg
1: bent tail fin edge: in this case this is a scar, caused by a bite (which way much more visible when the fish was smaller: for some time it had a mouth-edge-print on its tail fin!). because the cause is known and is non-genetic, this is not a reason not-to-breed with this fish.

2: bent pectoral fins. Both pectoral fins have downwards curved fin-rays. I don't know if this has a genetic basis, but I suspect that it could have. It may be a less-severe form of the bent fin-rays which I described before. This is a reason not to breed with this fish.

3: relatively short and round head shape. This is the head shape I expect in a 2 cm juvenile, but this particular fish is about 3 cm and should have a more "adult-shaped head". This is very difficult to judge from a photo, but in the aquarium it is very clear because the fish looks different from it's sibblings. I think that it is likely that this also has a genetic basis, so another reason not to breed with this fish.

- not visible on the photo: the fish is relatively small, compared to it's siblings. This may be caused by genetic factors or by a "bad start" (fish that are born small-sized stay behind because they are always the last at food and can ingest smaler morsels / less food than their siblings. Small differences at the start become large differences later on). In itself it gives mainly reasons to doupt about its health, together with the other characteristics it's very clear: this particular fish is not suitable for breeding.

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Re: 4: the domesticated cichlid

Post by illustrator » Sat Feb 21, 2009 4:08 am

Here are two pictures of the same young convict:
san1.jpg
right side looks normal ...
san2.jpg
but on the left side the pattern is a bit mixed up (see arrow)
There are a whole number of factors that can cause stripe-pattern changes. One of these factors is "coincidence", and the chance for "coincidence" might not be random at all. I'll try to explain:

The exact stripe pattern of a convict cichlid is genetically determined. Because of this, it would be logical if a fish has the same pattern on the right and left side (both sides of a fish are genetically the same). Small "mistakes" in the pattern can occur, and it is not always clear why. Water quality probably has an influence, but also inbreeding. Inbreeding makes fish more sensitive to all kinds of things, including water quality. So it is possible that inbreeding also increases the chance for small mistakes in stripe-patterns. This is the theory behind "fluctuating assymetry". So, the more assymetrical an animal it is, the more contaminated it's environment and/or the more sensitive it is (which might be due to inbreeding).

But it's up to a point quite random. That means, it hardly makes sense to select only the most regularly patterned fish from a certain litter: all brothers and sisters are equaly inbred, regardless of stripe-mistakes of individual fish. If this is all correct, it does make sense to choose fish from a litter where most fish are having a regular stripe-pattern. If most fish of a litter have stripe-mistakes, this might be a reason to either not take any of the litter, or to search very hard for some unrelated partners.

... but in some cases stripe-mistakes are simply due to a colour mutation and then this theory doesn't apply at all ...

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Re: 4: the domesticated cichlid

Post by Bas Pels » Sat Feb 21, 2009 5:27 am

Paul

Your obvservations are true untill a certain point. I think you forgot brothers and sisters, even say 5 generations inbred, can still have genetic differences (I'm not referring to eventuel sex genes, but others)
Therefore, I'd still choose 'the best' if a choise is available

But, that does not say I disagree with the point you are trying to make

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Re: 4: the domesticated cichlid

Post by illustrator » Sun Feb 22, 2009 3:46 am

You are right about that, however, they are equally inbred (inbreeding coefficient is the same) but there are genetic differences due to chance. Another thing: I doupt if anyone knows how frequent "stripe-mistakes" occur in natural populations. They certainly occur, I think in all striped species, and also without inbreeding. I think that we only have to worry when the frequency of "mistakes" becomes much higher than in nature. Would be interesing to see how many F1 fish show "stripe-mistakes" because these should show little effects of inbreeding.

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Re: 4: the domesticated cichlid

Post by illustrator » Wed Mar 18, 2009 5:29 am

Untill now I have been showing photo's of convict cichlids with nice contrasting stripes. They are not always like that: their colour varies with their mood. In general, when they are in a more agressive, territorial mood they are very brightly striped. At other times they can be unbelievably plain, almost boring. But to me, theye colour changes are yet another interesting part of observing convict cichlids. Leucistic (white) convicts can't change colour: they are always white. This limits their ability to express their mood, but it is very hard to figure out if this also influences their welfare in an aquarium. In any case, this is another reason why I prefer the "normal" wild-coloured (striped) ones.
visjes.jpg
Half-grow convict cichlids in a very plain colour-mood (non-agressive), hiding between plants.
visje.jpg
Half-grown convict cichlid in an "average" colour-mood, note the darker patches on the middle of the body.
vis.jpg
Juvenile convict cichlid in a contrasting (agressive) colour-mood.

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