And I'm going to disagree with all of you that are disagreeing with FG. You are all disagreeing due to a lack of "factual evidence" and in the process ignoring everything that is factually known about their lifestyle and their water chemistry needs.
I'm sorry, but 100 people on the internet claiming coexistence for 6 months or a year does not success make. Success in fish-keeping means keeping that fish alive for its normal aquarium life span without issue. That also would mean matching species by lifestyle and water chemistry needs. I challenge you to find more than a handful of people who have truly done that. Barring being able to find that, there is no factual basis for the statement that New Worlds and Old Worlds can successfully coexist in the same water conditions in the same tank.
Imagine how many "success" stories we would get if we put out a call for all those who have successfully kept old world or new world in separate aquariums over the years. Now go find me the few who have done it successfully long term the other way. Most people who make that claim quite frankly haven't even been in the hobby for a year.
For the most part, if you are in the hobby for over a year, you care enough about your fish to insure they are getting their needs meant in terms of water chemistry, space, and living conditions, and that means you aren't mixing Old World with New World. It has nothing to do with "I've been doing it successfully short term." The fact that it can be done, ignores the fact that in 99% of cases, it shouldn't.
Can it be done - probably, very few things in the aquarium world are impossible. Is it the best situation for the fish - never!
Sorry to say it, but bottom line, those of you who are claiming to be able to do it are not truly looking out for what is best for your fish. You are looking out for what is best for you.
1. I have been in the hobby more than year. Actually close to 30 years.
2. It is just a very broad statement to say no fish from a whole continent can be with any other fish from a whole continent.
3. They are not all completely different water perimeters. Some are overlapping as proven below.
4. I have stated plenty of Facts earlier in the thread. I have not received any facts back only theories. same with every other discussion I see like this only theories. I was told water perimeters were to different (please see below)
5. I am always looking out for the best interest of my fish. My peacocks are large beautiful adults and my Jack is coming along nicely. With no aggression between the species.
My argument is that people can't use a general statement that old and new world cichlids cant exist together. It is a case by case basis. Any blanket statement that consists of generalizing a whole continent is ignorant. That is my argument plain and simple.
Examples.
Would I put Mbuna with a Firemouth -
No MBuna will most likely terrorize and kill the firemouth.
Would I put Mbuna with a Dovi -
No The Dovi would make a quick snack of the mbuna.
Would I put GBR and Kribensis together -
Yes given the right tank size. Water perimeters over lap and temperament are similar.
Kribs 72-82° F, KH 3-10, pH 6.0-8.0
GBR 72-79° F, KH 5-12, pH 5.0-7.0
Would I put a Jack Dempsey with peacocks -
Yes Given the right tank size. Peacocks are an open water species with a hierarchy the mess with each other keeping each other in line at the mid level of the tank. Given you add that JD of similar size it will remain at the bottom in its selected territory. Typically paying no interest in the peacocks. If a peacock tries to mess the JD it can and will easily back down the peacock. However given they typically hang out in different areas of the water they rarely confront each other. This is the exact set up of my tank and I know of others with similar set ups.
Peacocks 76-82° F, KH 10-15, pH 7.8-8.6
Jack Dempsey 78-82° F, KH 5-12, pH 6.5-8.0
So that is my argument some species of fish can, do and will co exist regardless of the continent they come from so the blanket statement is not correct and we should educate people per the species selected.
As far as finding people to admit they keep them together on this site is going to be hard because it is known they will get crucified for admitting it on this site. I have seen it many times. Look on other sites and it is more freely spoken about.
Ps I rarely hear of these blood baths you all speak about. If they are so frequent I am sure we would see more posts on this site. But I don't see any.
PPS LOL. If some can just admit that it should be a case by case, or species by species, basis and not a blanket statement that would satisfy the argument.