Species mixing

I just got done reading the 'Species Mixing Disasters' article. Much of it was sensationalist, circumstantial and perhaps even apocryphal. The vast majority was simply the obvious. The moral of many were "Don't mix species from vastly different environments" and "Don't mix species of vastly different sizes" Uh, yeah. Just simply recalling the amphibian credo - "If it moves and I have even a chance of fitting in my mouth, I'm going to eat it!" - could have eliminated most of those disasters.

Some have taken the stories of these victims of the tragically obvious and used it as "proof" for their cult like campaign of never mixing species. I see it all over the 'net when herps are discussed. I even saw someone on one of those answers web sites respond to a questioner with "I've been collecting herps for 5 years and everyone knows that you never mix species."

Wow, 5 years! Well, I've been herping since 1965 (and yes, I'm fully aware how old that makes me) and seeing that and other similar statements stated in such absolute terms makes me want to scream, "Wrong!!!!"

Now don't get me wrong, there are many, many combinations that will not work, even same species in the same tank is sometimes a risk with some, but again, to state it with such certainty and as in the above reference, so arrogantly, just tees me off. Instead of telling these herpers, many of them inexperienced, never to mix species, how about telling them the truth - that though not mixing species is a good general rule of thumb - some combinations can work. I wonder if some these single species apostles have ever even tried some combinations or do they just believe what someone else has told them with a religious-like faith?

I'm not going to theorize or speculate here, I'm going to give examples from my own experience over the years. These are some of the successful setups that I have had and when I say 'successful setups' I mean that in terms of years, not weeks or months.

Green Anoles and Brown (Bahamian) Anoles
Sure, the browns are more aggressive and the greens can be a bit skittish, but it can work. Funny thing is with anoles, same species or not it's more important to limit a group to one male. I had 4 of each species, one male in each group. I took a somewhat large (55 gal) and set up arboreal areas at each end of the terrarium, with a flat area making up the middle third. They all mixed together at first in one area with some male jockeying and jostling, but after a few days, the greens went to one end while the browns stayed at the other. Things went along just fine with both groups staying out of each other's way with only occasional tree crossing. After about six months, the male brown decided that he wanted the side that the greens were on and his females followed. The greens simply moved to the other end of the enclosure and they all lived happily ever after.

Turtles
With baby turtles, I had red-eared sliders, river cooters, map turtles, musk turtles, mud turtles and soft shelled turtles all together without incident. I did keep the baby snapping turtle all by himself though. Not being aware of their need for UV light at the time (this was the late 1960s and UV light bulbs weren't readily available and expensive even if I had the knowledge), they were all gone within a year. Ok, this one can't be measured in years but they all did get along, no squabbles and everyone ate well. As a sidebar, the literature available on herps in those days was limited, lacking in essential info and often flat out wrong. I still have many of those books and that will be a subject of a later post.

Later, I did have sub-adult (4-5 in) red-ears, map turtles and painted turtles together quite harmoniously in the early 70's. I by then had learned about UV and had my father adapt one those black lights used for hippie posters back in the day. I had them in a large (75 gal) set up and after a few years they got too big for even that setup so I ended up having to give them away.

In an outdoor setup, I had an ornate box turtle, a three toed box turtle and a tortoise which was either a desert or a Berlandier's tortoise. Again, no issues in compatibility and I had these guys 10 years or so. Proper hibernation was an issue (southern California didn't get cold enough each winter) and that led to the demise of two of them eventually. I turned the three toed box loose in the backyard and he survived quite a few more years as a "free ranger".

Anurans
My big setup (75 gal again) had green tree frogs (2), grey tree frogs (2), barking tree frogs (2) and Cuban tree frogs (4). Once I got a filtration system for the water I also added some leopard frogs (2) and a green frog (Rana clamitans). This was one of my favorites. It was quite a sight when I would dump in a load of crickets and our house guests always were amazed to watch the predators at work! Back then (early 80's) I could get 500 crickets for $5. Four years later, the only casualties were one Cuban tree frog and the Rana clamitans. By this time, my 2nd child was born, the herp room needed to become a child's bedroom, so I had to give these guys away and my herping days were over for a while.

I also kept Western Toads (backyard caught) with Texas toads and Southern toads together with no issues. In fact, I would speculate (I know I said I wouldn't, but indulge me here) that most Bufos of similar size can be kept together; I've had several other Bufonids species and they're mostly non-territorial and non-competitive as a rule.

Caudates
Kept C. Orientalis with Eastern Newts. For the time the Orientalis were similar size as the Eastern newts, everything went swimmingly. Though I had no evidence of any problems, once Orientalis got noticeably bigger I separated them as a precaution.

Now, of course since I started as a small kid and printed information was limited or simply incorrect and pet shop people had little clue (some things don't change do they), I also have many "Hmm, that wasn't such a good idea" experiences. I will relate one.

I had a 10 gallon setup with a few fish (don't remember which kind), a crayfish and a baby southern painted turtle. Everything was fine until (here it comes!), the crayfish - who had been bashful and unassertive - molted. Even though he only grew a small amount, his claws doubled in size. He seemed to realize that because he became aggressive even towards me! That should have been a red flag but hey, when you're 15 or so and all had been going well in the tank...One night, while I slept, the crayfish caught the turtle. When I awoke the next morning, I found the turtle in the crayfish's clutches, obviously drowned and with one of his hind legs chewed off. Sorry about that Mr. Painted Turtle.

If you've made it his far, I thank you for your patience. Sorry about the length, but I felt I had a point to make.

Mal

Thank you VERY VERY much.

I've mixed Ocadia sinensis with red eared sliders, map turtles and reeve's turtles. I've had rice frogs with pacman frogs. I've had firebellied toads with tree frogs. I have P. chinensis with P. labiatus.

You are right.

Well, so you think the only problem with mixing is agression?
What about patogens? stress? potentially dangerous differences in both toxins and biology?

I´m not going to talk about the other mixes because they don´t really concern me, and turtles and anoles are not the same as caudates and i think they can hardly be compared.
Mixing C.orientalis with N.viridescens is a bad idea for many reasons. In this case agression is very unlikely....but given that both Notos and Cynops are WC, the possibility of exchanging patogens is big. Also, male notos have a particular way of displaying to females that can actually drown a Cynops....
When we talk about mixing and we categorically say mixing is a bad idea is because it involves risks, and most of us seem to think that taking those risks is irresponsible.

"When we talk about mixing and we categorically say mixing is a bad idea is because it involves risks, and most of us seem to think that taking those risks is irresponsible."

Introducing a newly acquired creature of the same species into the tank even after a decent length quarantine is still a risk as I'm sure you'll concede.

Oh, and I hope you're not accusing me of being irresponsible. I was collecting and keeping herps including caudates before you were even a fertilized egg. No offense intended Mr Moderator.

I gave real life examples of species mixing that have worked for me. Please spare the knee-jerk reaction and tell me where I was wrong.

"Well, so you think the only problem with mixing is agression?

Never said that. But "getting along" and thriving together for years would be my definition of 'successful'.

What about patogens? stress? potentially dangerous differences in both toxins and biology?"

As you certainly know, with WC pathogens and stress can be a problem even with the same species so that's a common issue. If toxins are incompatible, then of course they should not be kept together. But how do we learn who's compatible with whom? Maybe from those with the voice of many years of admittedly trial and error experience, that is if you're willing to listen.

I honestly have no idea how someone can be so passionately 'pro-mixing'. It would just never occur to me to be an ideal situation that I'd actually set up on purpose. What is the point of mixing? What are the benefits? Beyond simply not having the resources to provide a separate home for each species.

I agree that mixing certain species is possible given a large enough enclosure, plenty of hiding places, etc. One of the problems with newts however, particularly commonly available WC species such as C. orientalis, is that they are most often seen mixed in with crabs, frogs, fish and so on at many petstores and this gives the false impression that this is the ideal environment. Add to this the fact that so many newcomers to the hobby want to mix species without having appropriate knowledge or experience and the end result is most often a 'disaster'.
This forum always welcomes every viewpoint however your original post comes off a little strong (as in rude). The people that contribute to both this site and caudata culture are providing a wealth of valuable information for free. This information is based on years of experience from hobbyists from around the globe and while you are correct that much of it is anecdotal, it is still better than anything else out there (in English).
I cannot comment on your experience with frogs or turtles because I have limited experience with these animals myself. I was an anole hobbyist for about eight years however, having bred around a dozen or so different species. Anoles by nature are very territorial, with dominate males defending large (proportionate to the size of the animal) home ranges in the wild. If you think that eight individuals crammed into a 55 gal aquarium are living happily ever after then you are deluding yourself.
Chip

Agreed. Mixing CAN be succesfull...but the species involved and the space required are huge factors in that. Years of trial and error have shown that some mixes are simply never going to work. Others might appear to work but ultimately have an effect on the animals.
I think there´s a huge difference between surviving and thriving. A lot of species can survive together....very few can thrive.
The article on CC is mostly intended to new hobbyists(by far the ones that are most likely to be interested in mixing species), and since mixing is VERY RARELY succesfull, and requires particular housing and most of all, it requires some degree of experience to be able to tell if an animal is ok or not....the GENERAL advice is NOT to mix. This is in favour of the hobbyists, as it will prevent him from making silly mixes, and will create a concience of what mixing might end up like.
From what i see in most cases of mixing, the owners usually fail to distinguish between "surviving" and "thriving", so it appears that the animals are doing ok..and may continue to look so for years, but eventually you are most likely to see side effects.

I really think what you see as sensationalism, is only an extra effort to try and educate....because let´s face it, most people know squad about this animals and are likely to make some very surreal and catastrophic mixes.


About mixing Notos and Cynops i really think that´s a risky businness even though agression is scarcely a possibility.

It´s obvious that opinions about this particular situation are bound to be different as with most aspects of caudate husbandry, but i don´t think it´s fair you saying that we treat the situation with sensationalism or "false proof", because it´s an opinion based on lots of years of communal knowledge and it´s only intention is to prevent and educate.

I too think it´s funny how some poeple seem to be practically obssesed with mixing...i´ll never understand it myself, but as long as it doesn´t put the animals health or quality of life in jeopardy, it´s fine....sadly most cases are indeed risky( even though people don´t seem to like admitting it).

That's a pretty cocky post for only your second on the site. This is a newt and salamander site. We do have discussions regarding anurans and gymnophiona but those are limited. Our remit is limited to amphibians, not reptiles. Considering we are talking about two different taxonomic Classes of animals, I personally don't see much commonality between them, and consequently I don't see the relevance of your reptile examples here unless you're on some kind of herp mixing crusade.

1965 is long before I was a fertilized egg too, but I'll match my amphibian knowledge and experience, and my biology experience and education, against anyone's experience any day. I view myself as only qualified to comment on your amphibian mixing. Before I do so, you should know that those articles about species mixing have been reviewed by several professional amphibian keepers (including more than one zoo curator of amphibians, and individuals who have published peer-reviewed journal articles on amphibians).

Now regarding the amphibian mixing, my philosophy on this is that if species exist sympatrically in the wild and they do not prey upon each other, then I would accept mixing them. For that reason, your Gray Tree Frogs, Green Tree Frogs, Barking Treefrogs, and perhaps the two Rana species, would be acceptable in a large enclosure (the Cuban Treefrog definitely would not be acceptable). My primary concern would be mixing parasites and pathogens between species that ordinarily do not come into contact.

That last point covers your Cynops orientalis and Notophthalmus mixing - I view that as playing with fire. Nothing happened? That proves nothing. I could run back and forth across a highway and not get hit by cars but that doesn't mean it's not dangerous. How do you like that analogy. I think it's pretty accurate.

Of course, your mileage may vary, as they say, but your good fortune with regard to problems is not the most common experience. What I will say for you is that at least you are not some kid who has kept a few species together for 4 months and then proclaims to the site that their collective wisdom is bogus.

I would like to see some documented data from valid sources to back up your statements.

Anecdotal, unsubstantiated information is rarely viewed as valid anywhere, however true it may be.

I have to say I'm not all for mixing species.

The only time it ever occurred to me to mix species was when I put different types of fish in a 55gal tank when I was a teenager. My big mix was putting some neon tetra, danio and guppies together, I had a male guppy, 3 female guppy, 4 neon tetra and 4 danio.

People have mixed brown and green anole successfully, I've even heard reports of them interbreeding.

I have seen red-eared sliders, yellow-bellied sliders and river cooters mixed together. I wouldn't know of other turtle or tortoise mix.

But as far as bad caudate mix, the worse I've ever seen was at the Tennessee Aquarium in Chattanooga,TN. They had an exhibit with 2 P. Labiatus, a P. Hongkongensis and a T. Shanjing. The P. Hongkongensis was hiding under rocks in the water, the P. Labiatus were both very thin and one had fungus on his head and the T. Shanjing was hiding on the land area. The exhibit was a nice size one but I really don't believe that the animal were thriving.

I believe some species mix are possible but not with caudates. I honestly think you can have a much more appropriate set-up in which your animals can thrive if you keep only one specie in it.

I just have to wonder one thing though. Has anyone ever mixed subspecies? I just thought of the different types of Notophtalmus and wondered if anyone ever thought "hey I'll put some of those together and see if they can interbreed?", same thought crosses my mind about Necturus sp.
I just want to know if this has ever happened, the thought of doing so myself has not crossed my mind.

Mixing subspecies will just muddy up the genetics. If your goal is breeding, mixing subspecies is a terrible idea. Hybrids contribute nothing to genetic lines.

Kaysie said:

Mixing subspecies will just muddy up the genetics. If your goal is breeding, mixing subspecies is a terrible idea. Hybrids contribute nothing to genetic lines.

Click to expand...

I was just wondering if anyone had ever done it, I think the idea of purposefully making hybrids is irresponsible. I hope I didn't give anyone the idea to do so.

I have another question though. Haven't axolotls been mixed with tiger salamanders at one point in time to obtain new color morphs?

slowfoot: People read what they want to read I suppose. Nowhere would it indicate that I'm "obsessed" with mixing. In fact, I've had and have many single species setup. May main complaint was the notion that it is totally, absolutely unacceptable and can only result in disaster. You'll note I mention that many, many (which should imply 'most') combinations DON'T work. However, since we are here to share experiences, I shared some of mine.

freves:"If you think that eight individuals (anoles) crammed into a 55 gal aquarium are living happily ever after then you are deluding yourself"
Now I'll admit that they didn't actually speak to me and tell they love it in my 55 gal, but going by their appearance, their demeanor, their appetites and their behavior(s) they would seemed to have been quite content. As I'm sure you'll concede, if one keeps a species long enough one gets a pretty good feel for signs of satisfaction or dissatisfaction with the environment from its inhabitants.

azhael: Ah, so it is an organized propaganda campaign to convince newer keepers from species mixing? In that context I can understand where you're coming from and it makes some sense. However, what you and others have created are a flock of 'never, ever, ever mix species' converts going all over the 'net in all areas of herping and preaching their new found faith as if it were gospel truth. Of course, that was the plan all along I'll wager.

John:You sound pretty cocky yourself, but then again, you control the balls, the bats, and the cather's mitt, the rest of us are only in the game here. I maybe should have added, 'often works best when species coexist in the wild without predation'. In the spirit of full disclosure: My c. orientalis and noto mix was a long time ago and truth be told, I would not combine them now. But the fact remains, I had experiences to share and they are as valid and real as any others. Hey, we're all in this hobby together after all. See you on the highway.

PS John: I'm glad to see that you framed your species mixing statement as your "philosophy". That's reasonable and non-absolutist and a far cry from the screeching 'never, never, ever, ever' that I keep hearing.

SludgeMunkey:"I would like to see some documented data from valid sources to back up your statements"
Yeah you're right, let's not believe anything about anyone's personal anecdotes as related on this or any other web board especially if it flies in the face of truths held so dearly. In fact, I want documented proof that you are SludgeMunkey.
"Anecdotal, unsubstantiated information is rarely viewed as valid anywhere, however true it may be."
Think about that statement you made for just a second, then drink three glasses of cold water.

Mal

malduroque said:

slowfoot: People read what they want to read I suppose. Nowhere would it indicate that I'm "obsessed" with mixing. In fact, I've had and have many single species setup. May main complaint was the notion that it is totally, absolutely unacceptable and can only result in disaster. You'll note I mention that many, many (which should imply 'most') combinations DON'T work. However, since we are here to share experiences, I shared some of mine.

Click to expand...

You used the word 'obsessed', I didn't.

My main question though is: what are the benefits of mixing? Why should anyone mix? Why isn't it just something that should be automatically discarded because it's not the ideal situation? I've heard a few justifications for mixing: (1) not enough space, money, resources, to house separately, (2) someone wanted a more 'exciting' vivarium, or (3) they just wanted to see what would happen when they put two species together. Those just don't seem like compelling reasons. If there are others, please enlighten me.

Regarding this issue in general, I consider Caudata Culture's stance on species mixing to be completely appropriate. This website provides a TON of information, especially for the folks who need it most...newbies. As a novice, I would not have considered the negative aspects of species mixing, and without this site would have made some poor choices starting out. As I've learned more about the hobby, and earned advanced degrees in biology, I now understand the dangers well enough to work around a few of them.

Malduroque, you have mentioned two amphibian-mixing examples that, in my experience, can work. One involves similarly-sized tree frog species with similar ecological requirements. Although you were probably already aware that some of your species (R. clamitans, O. septentrionalis) would eventually grow to a size large enough to eat the others, you were able to monitor this and keep them successfully. In our university research laboratories, we successfully maintain mixed species treefrog tanks with no incidence of disease, aggression, or predation (and have done this for over 10 years).

The other example involves peaceful newt species of similar size. We should remember that even the most spacious captive environments are constraining newts to live at an unnaturally high density, regardless whether the individuals are of the same species. This can sometimes cause even the most peaceful individuals to attack each other. In this respect, my best analogy for keeping newts is like keeping cichlids. You cannot predict when aggression will start to cause problems, but you should always be equipped to separate animals if some individuals become stressed. Aggression levels vary greatly among individuals and also varies throughout the year, but it is not impossible to get a group of multiple species (captive reared, no toxicity issues, similar size...) to share the same tank without issues. You must also understand the species' sensitivity to other species' toxins, and be prepared to deal with the potential for hybridization. However, if all this were easy, we wouldn't have a list of 58 disaster stories as evidence to the contrary.

Novice amphibian keepers are up against a sharp learning curve regarding the ability to identify a stressed animal, regardless whether it is due to aggression, water quality, or other issues. Malduroque, I hope you'll agree that since so few species combinations offer the slight possibility of success, it is prudent to advise novice amphibian keepers to stick with single species tanks. It simply averts one more challenge that awaits the newbies, and in the long run, increases their chances for success.

Letting my opinion rest, I agree that there is a stigma regarding this issue. Maintaining multiple species in a setup does not directly cause animals to attack or eat each other. Nor does it directly increase the chance of transmitting disease among animals. We are left to rely on the theoretical possibilities until better information is brought forth. I guess until then, I would rather err on the side of caution, and urge people to reduce the chance of complication which is more likely when multiple species are kept together.

Mal - if I'm reading you correctly, what you are saying is basically... we have presented some reasons for not mixing (both in the article you read and in this forum), and thus we are responsible for creating "a flock of 'never, ever, ever mix species' converts going all over the 'net in all areas of herping and preaching their new found faith as if it were gospel truth". All we are doing is presenting evidence (yes, anecdotal) and our own opinions. What I don't understand is how this website is somehow responsible for all these "converts" you've met. I sense a lot of vehemence on your part, I can only imagine that some of your encounters with these "converts" must have been heated. Yet, we all seem to be agreeing on more points than we are disagreeing. What exactly do you think caudata.org should be doing differently?

(Maybe caudata.org should be flattered that we've somehow turned the tide of public opinion against mixing species. Are we really that powerful and almightly? I think not.)

Based on your other posts, I guess you'll find something to nitpick in what I've said. Something that proves that I'm just a young wippersnapper who ought to stay under a rock somewhere and keep my anecdotes and opinions to myself. Have at it!

A couple of starting comments on what can be a very long contentions thread...

When discussing captive animal welfare there tends to be a progression in both Zoos and the herpetoculturist sectors that is very similar. This tends to proceed along these lines
1) keeping the animal alive for a length of time
2) keeping the animal alive long enough to breed it
3) keeping the animal alive long enough to reach maximal longevity (not median, maximal)
4) breed the animal sufficiently frequently enough to replace or exceed loss due to death
5) all of the above and keep the animals in such a fashion as to allow for as many natural behaviors as possible.

With respect to many caudates we are still working out 1-4 much less 5.. but there are some where we have achieved a pretty good record of 1-4 and now can work on #5. Wth many amphibians unless there is a lot of forethought put into a multispecies enclosure, these goals cannot be achieved most of the time.

With respect to mixing species from disparate geographic zones, this is has become a problem with emerging infectious diseases (EID) in amphibians (and other herps) such as that seen with the transport of Ambystomids to new locals and the introduction of viruses to novel locations which can really significantly cause problems with not only the amphibians native to that site but depending on the virus strain fish as well. (I will mention reptiles once with another example.. look at the data on mycoplasma in native North American Tortoises and note that it has also now been found in native box turtles....) EIDs are a problem even if you are never going to release the animals as the waste water is going to carry the pathogen (unless you take specific precautions to prevent it) as most waste water treatment plants (assuming you aren't dumping the water in the yard) are not set-up to handle these wastes and many large cities, rain water is funneled into the waste treatment system with the result that untreated waste can be discharged when large storms occur and overwhelm the system.

Multispecies enclosures are possible but in many cases are unadvised unless a lot of care and forethought are put into them and the species are chosen with specific care towards thier long term success and care.

Ed

slowfoot: "You used the word 'obsessed', I didn't."
You don't really read things do you? I used the word 'obsessed' with regard to the blanket non-mixers that I've encountered. I never used that word with regard to myself as you accused me of. First, you put words in my mouth, then you back pedal to hide your error. Now re-read my original post and prove me wrong. Go ahead, do it.

I will answer your more substantive question though. I've always seen terrariums as little slices of nature, a mini-world if you will. To me, it's not just an enclosure that serves the animals but an aesthetic statement unto itself. To that end, I've always, to the best of my abilities, tried to design them to reflect that, a kind of natural synergy within an artificial environment. So, in stocking the flora, I go for variety, in stocking the fauna, I try to go for variety as much as possible keeping in mind the needs of both the creatures and the plants that I would put together and yes, there are combinations that work some of which I have highlighted. The short answer: it's an aesthetic choice.

kwksand:"Malduroque, I hope you'll agree that since so few species combinations offer the slight possibility of success, it is prudent to advise novice amphibian keepers to stick with single species tanks. It simply averts one more challenge that awaits the newbies, and in the long run, increases their chances for success."
Well, I can't disagree with anything you've said and one thing you fine folks at caudates have caused me to shift my opinion a little on is encouraging newbies to mix species. I'll still fight that hard-line of 'no, no, never, never', and I'm not fond of obfuscating the truth with horror stories, but I will concede that it may be for the best. In short, I can agree with some of the sentiment I just am a bit uneasy with the methods. Tnen again, wouldn't it be fair to tell them the following combinations have worked and the degree of difficulty in making it work?? It is a tough one.

Jennewt:"Based on your other posts, I guess you'll find something to nitpick in what I've said. Something that proves that I'm just a young wippersnapper who ought to stay under a rock somewhere and keep my anecdotes and opinions to myself. Have at it!"

Why Jen, you're much too sensitive and no I don't believe that you live under a rock, in fact I'm quite sure that you're fully diurnal. My main beef is not what posters have said here, I was reacting to the monster, chiller, horror page 'Species mixing disasters' that is on this site and yes, I've run across too many 'everybody knows that you NEVER mix species" types in my cyber-travels. All I did was point out that statement is not completely true, with real world examples. I really have no problems with those who have thought this issue through and have decided to go all mono-species, it's just those 'nope, never, case closed. I've been herping 3 weeks, and someone told me on a website' types who strike me as kool aid drinkers.

It reminds me of those anti-drug campaigns I used to see in the 60's and early 70's. They had enough ammunition with the actual truth to warn about the perils of drug abuse, but no, they insisted on sensationalism, hyperbole, and half to non-truths. Scare tactics and an insult to the intelligence. (and no. I'm not equating species mixing to taking drugs. Barking Tree frogs anyone?)

Oh, and Jen FWIW at least I can say that when I started with herps you were not just a fertilized egg, you were ambulatory and just entering the potty training stage.

Mend your attitude or leave the forum. I don't mind you stating your opinions but the way in which you do so is condescending and boorish. Act that age you keep bringing up.

I also like naturalistic tanks, big fan of them, but you cannot compare a tank with a piece of nature. No matter how complicated, varied or well managed a terrarium might be, it will never even be close to being a piece of nature.
You cannot find the equilibrium that nature has within the limits of a crystal tank. That´s why it´s called captivity hehe.
This also means that even species that occur naturally in the same areas are not necessarily going to do well if kept together in captivity. It´s a bit of an off example but take a look at lions and hyenas...they both have similar biologies and both share habitat....try to keep them together though.
I can say without a doubt that non of the cases of mixing that i´ve read about were good ideas. People tend to defend mixing passionately, saying that we are all wrong instead of showing proof. Ok, that´s not your case, you have your experience behind you, but i really think as most mixers you are missing a few points that are important even though they are not obvious.
Mixing invariably comes with risks, and has no benefit for the animals whatsoever. The only benefits are for the keeper, which i personally find very selfish. Our goal is to provide the best care we can possibly offer to our animals, and taking risks is probably not the best aproach...

CC´s information is there to educate, and i think it´s a very valuable lesson that mixing is not in the best interest of the animals. You say the examples are sensationalistic...well, i say they are all true cases....people have actually done those mixes, with the horrible consequences they had. I think as well as we are here to learn from the experience of others, we are also here to learn about the mistakes of others...and there have been loooots of mistakes involving mixing(and i have yet to hear from a trully successfull mix of caudates).