Decreased aggression in captive bred fish.

[tiger15]

Imo that’s due to the fact that Convict mature faster as they attain a smaller size than most other fish. A 4 inch Convict is essentially a sub adult/fully grown compared to say, a 4 inch Jaguar cichlid, which is still very much a juvenile. I could be wrong but that’s just what I think

True, it’s not fair to compare aggressiveness with size alone, as the ultimate size and stage of development must factor in. But I have kept gentler convicts such as Nanoleutus and Cutteri that are no where as aggressive as TBar , Panamensis or common convict.

Experiences seem to vary, but there was this study: Aquarium fishes are more aggressive in reduced environments, new study finds

In the early 1970s a friend of mine had an oscar he tried growing out with a convict and a (larger) jack dempsey-- not betting my life on my memory of his tank size, but it was a 55, I believe, possibly larger but 55 sticks in my head. The oscar killed them both and anything else he tried to keep with it.

When I was keeping/breeding African cichlids, I sometimes kept an A. rivulatus green terror with them to keep order; even smaller GTs were not intimidated and none of my haps, peacocks, or even mbuna messed with them. First time I did this was with a 2.5-3 inch green terror and I forget which mbuna species immediately went and flared at him. The GT did a right back at you display and that was that. I had some wild A. rivulatus at one point, they wanted to fight everything all the time. I tried putting them in different tanks but even at three inches they were too aggressive for my African cichlds.

Here's what Wayne Leibel had to say about the early, wild A. rivulatus in the hobby. Don't get confused, the quotes below are about rivulatus, not stalsbergi-- stalsbergi is from Peru, not Ecuador:



...after mentioning the rarity and high price of these orange/red rivulatus, he says:
https://www.tfhdigital.com/tfh/201005/?pg=35#pg35

My experience is the opposite. My first GT was kept with MBUNA. A Melanochromis chipoki locked jaw with a GT twice it’s size for half an hour until the GT gave in. From then on, the GT wouldnt dare to come near the Chipoki. The Chipoki ultimately killed half the MBUNA tank mates. I have never kept wild GT and no doubt they can be more aggressive. The domesticated strain GT I kept were relatively peaceful. I was able to raise several GT brothers to adulthood in a 75 g at peace. Although they engaged in low level of sparring, that had not elevated to murder as Mubuna did. My GT never bothered other fish, including smaller Leulupi and one angel tank mates as you can see in the video. Sorry the video resolution is poor as it was taken in an old camera of the 90s.

 

[Toiletcar]

Trichromis SALVINI and TRIMAC "Correction"

Clearly the scientists have got it all wrong - again... Timacs and Tricolor Cichlids are the closest relative's to eachother. At the moment, Trichromis salvini is on its own yet it's clear that the two species in question have been divided by ignorance. Timacs have been joined up with the...

www.monsterfishkeepers.com

Some ithyologists propose grouping Salvini and Trimac in the same genus.

False. Salvini are actually closely related to thorichthys.

 

[Hybridfish7]

Trichromis SALVINI and TRIMAC "Correction"

Clearly the scientists have got it all wrong - again... Timacs and Tricolor Cichlids are the closest relative's to eachother. At the moment, Trichromis salvini is on its own yet it's clear that the two species in question have been divided by ignorance. Timacs have been joined up with the...

www.monsterfishkeepers.com

Some ithyologists propose grouping Salvini and Trimac in the same genus.

Juan Miguel Artigas Azas wrote a paper on this same subject, saying that Trimacs should be moved in to trichromis, it's just that dna evidence doesn't support this.

No offense to him, but you are getting the trichromis trimaculatus thing from a guy who says cribroheros should be in thorichthys because one has the common name "false firemouth". There is a frog with the common name "mountain chicken". There is a reason we use sci names as much as we can.

 

[Toiletcar]

It’s shocking to people, because salvini doesn’t look or behave the same as any thorichthys. But this happens in nature. Some related species can evolve differently, finding their own niche. Salvini are more predatory than thorichthys. It’s an ambush predator much like parachromis so doesn’t live in groups like thorichthys. Doesn’t mean they should be a parachromis either. The interesting thing is salvini is often found w/ multiple thorichthys species. I don’t think it’s common for different species of the same genus to live together. I cannot find anything written by anyone other than hobbiest suggesting trimac is closely related to salvini. I like to follow the science and love learning about what ichthyologist discover.

 

[jjohnwm]

It might be worth keeping in mind that modern methods of determining lineage are constantly improving, DNA analysis being a prime example. Historically imagined relationships between different animals were clarified, confirmed, proven false and otherwise proven by DNA analysis. BUT...all this does is confirm which species are more closely related to which other species, and which groups are descended from which ancestral other ancestral groups. We can now categorically state that Fish A and Fish B are much more closely related to each other than to Fish C, regardless of how they look, how they behave, etc. This shuts down a lot of arguments.

It does very little to prevent the discussions...like this one...regarding which species is or is not a true distinct species, as opposed to being merely subspecies or geographical variations. Same with genera, which seems to be the current battle front. As stated above, not that many years ago all these fish were lumped into Cichlasoma, which seems by modern interpretation to be ridiculous...but as someone else also stated, at the rate we are going, every fish will have not only its own species, but its own unique genus as well. Equally ridiculous.

The science can show us how closely or distantly related various organisms are...but it is still entirely up to interpretation where to draw the line between subspecies, between species and between genera. We keep hearing that "A lot has changed since the bad old days!" Nope...actually, nothing has changed, except how we decide or disagree to apply the terminology. The fish are the same, and their genetic relationship to each other is the same; it's just that we can't agree how to talk about it.

If you seriously believe that much of the scientific community's bickering is based upon anything other than a desire for personal advancement and recognition by many researchers, who desperately want to create a name for themselves and be considered relevant by selecting some new area of taxonomy and then turning it on its ear...then I don't think that you are seeing the big picture.

The wood flooring on my outdoor deck is tan in colour; my wife calls it taupe; and I think the retailer referred to it as "khaki" or some such marketing BS. It's the same stuff as it was when I laid it down originally, still looks the same, hasn't altered its chemical structure or functionality one iota...but, wow, it seems to be so important to some people that we all refer to it the same way...and it has to be their way...

 

[Hybridfish7]

at the rate we are going, every fish will have not only its own species, but its own unique genus as well. Equally ridiculous.

I believe there is a balance, obviously we can go as far as to give everything it's own genus based solely on the fact that it is distinct enough to be considered it's own species, but this would make the concept of a genus essentially a redundancy, and solely kept to help you distinguish between species that share a species name. Meanwhile you can alternatively go as far as to take the literal textbook definition of a species and consider everything regional variants of one species based on the fact that they can produce fertile offspring. I had a biology teacher in highschool who insisted jack dempsies were "another kind of convict" because they're able to produce fertile offspring. I personally think the best route is the one we're going on now, get the genetic testing done on everything to figure out where everything truly lies. If there's time and funding, go back and mess with localities to classify subspecies to satisfy the need for specification. Iirc lepomis is currently taking that route, I believe megalotis is getting broken into 2 - 3 subspecies.

Leading off of that, I agree that no matter what we call them they're still whatever they've been for the last hundreds of thousands of not millions of years, hence I believe genetic testing will help us figure out what is what and what truly goes where for the sake of our comprehension.

 

[tiger15]

Genetic testing is not a magic wang to distinguish closely related species. There are hundred species of Lake Victoria cichlid identified by scientist, yet genetic testing slowed no difference in DNA. So species identification of Victorian can only rely on traditional color and morphology. May be they are not species, just subspecies or race. All CA originated from a single line of ancestry in recent geologic time, so are all Malawian cichlid. This is why these closely related fish can cross breed and produce fertile youngs. So it is not too wrong to say that JD is just another convict. I doubt you can use DNA to tell whether Salvini is closer to Trimac or Thorichthy, but morphological, Salvini is closer to Trimac. Recent DNA testing showed that Melanuras and Synspillum are one and the same species despite disagreement based on morphology by many fish hobbyists and importer such as Jeff Rapp.

 

[jjohnwm]

...Genetic testing is not a magic wang...

Ah, yes...the proverbial "magic wang"...

No, DNA cannot distinguish between closely related species...but it can, by definition, clarify which are more closely or less closely related to one another, which share common ancestors and how far back the divergence occurred. It still requires interpretation by scientists...and there is never complete agreement among them regarding how to interpret this data. Again, the picture being drawn by DNA analysis is a complex tree showing relationships...but the lines that divide one subspecies, species or genus from the next are still drawn on that diagram, quite arbitrarily, by the hands of scientists who can and do have varying motivations and preconceptions.

Can you cite a source for the comment about no detectable differences between various Malawi cichlids? That sounds frankly unbelievable. DNA testing has been used to determine which portion of a particular species' range a particular specimen originated from. It's used by Fish and Game departments to investigate poached trophies.

Recently-diverged species such as Malawi cichlids, Galapagos finches and tortoises, and many others would certainly show very few and/or small differences, but the difference must exist for them to be distinct...not necessarily distinct species, but distinct from one another. Otherwise, every spawn would produce the makings of a mixed Malawi community tank. If the DNA analysis is not carried to a fine enough degree and these differences are not seen...that does not mean that they do not exist. A case could be made...probably has been made... that all those multicoloured Malawis are simply subspecies of one varied species. BUT...that is, once more, merely semantics. Whether some/most/all/none of today's researchers believe one notion or the other, it changes...absolutely nothing. And when the pendulum swings back toward the "splitters", all that nomenclature will change yet again...but it will be just nomenclature. The fish remain...the fish.

 

[Milingu]

Genetic testing is not a magic wang to distinguish closely related species. There are hundred species of Lake Victoria cichlid identified by scientist, yet genetic testing slowed no difference in DNA. So species identification of Victorian can only rely on traditional color and morphology.

That is oudated. There is difference. Enough to provide data at what time the linage diversification started or that the original endemic fauna survived the last desiccation. Genetic testing and analysing is getting better and better and also cheaper.

 

[neutrino]

That is oudated. There is difference. Enough to provide data at what time the linage diversification started or that the original endemic fauna survived the last desiccation. Genetic testing and analysing is getting better and better and also cheaper.

Agree. Also, the model requiring 'hundreds of thousands or millions of years' for species radiation and adaptation to ecological niches is outdated, making the "these fish have lived in X conditions for millions of years" argument outdated when you pair genetic research with knowing a little about the climate and ecological history of some of these places.

https://academic.oup.com/mbe/article/38/8/3111/6179338

In particular, Lake Victoria contains >500 endemic species that were generated in just 14,600 years after it dried up at the end of the Pleistocene (Johnson et al. 2000). The level of genetic differentiation among species is considered to be very low due to the short period of time after speciation (Samonte et al. 2007), which gives us a great opportunity to find candidate genes that have contributed to speciation and adaptation. In other words, the genetic differentiation among species can be used to find the signatures of natural selection that occurred during the speciation and adaptation of Lake Victoria cichlids.

And if you think that's fast:
https://royalsocietypublishing.org/doi/10.1098/rspb.1990.0052

Major low levels of Lake Malawi and their implications for speciation rates in cichlid fishes

...methods show that lacustrine sedimentation had resumed by about 1860. At this time, early explorers, such as Livingstone, were reporting evidence of rising lake levels. Hydrological modelling shows that the lake-level changes indicated are possible in the timespan available.

The species flock of rocky-shore dwelling Lake Malawi cichlids known as `Mbuna' contains about 200 species in Malawi's waters. Mitochondrial DNA differentiation shows that the flock as a whole is of extremely recent origin. Almost every rocky outcrop and island has a unique Mbuna fauna, with endemic colour forms and species. As many of these islands and outcrops were dry land within the last 200-300 years, the establishment of the faunas has taken place within that time. The present diversity of the Malawi cichlid-species flock, and particularly the Mbuna, may be readily explained by the rapidity with which small founder populations can diverge from the parent population, as demonstrated by the present chronological evidence on changes in lake levels and by the Mbuna distribution data.