Micropoecilia Picta

[catxx]

I saw the Micropoecilia picta in Wildwoods at the weekend and was particularly tempted, but apparently they're best in brackish, something I haven't done before.

Those who keep these guys, how do you keep yours? I currently only have Endlers and Girardinus metallicus (not in the same tank!), and hope to upgrade the Girardinus metallicus into a bigger sub-tropical tank and with a bigger shoal when I move just after Christmas. But these are freshwater, not salty.

Turns out I have a "thing" for mini livebearers!

 

[nmonks]

There's some debate about whether they absolutely must have brackish water. Some aquarists insist they don't need it, while Fishbase (and most quality books) insist they come from slightly brackish water habitats. It's worth mentioning that Limia are brackish water fish in the wild, but do just fine even in just moderately hard freshwater. Conversely, mollies are mostly freshwater fish in the wild, and yet are unquestionably easier to keep in slightly brackish water.

One way to look at this might be to ask yourself whether adding a little salt, say, 3-5 grammes/litre, would cause any problems. It certainly won't cause any harm, and if it is important, that should be enough to keep your swamp guppies happy. If you're keeping them all by themselves, then adding a little salt would be a no-brainer.

Cheers, Neale

 

[catxx]

They would be alone (maybe a nerite for company), but currently it's just a 25L I have going spare that's set up. Would that be too small for a trio to see how I get on with them?

 

[nmonks]

That is a little on the small side, but it should work out fine for just three specimens. As their numbers build up, you may find upgrading to an 30 or 40 litre tank makes sense. The nerite, by the way, won't mind the salt at all, and nor do algae-eating shrimps.

Cheers, Neale

 

[catxx]

That's why I thought Nerite over any other . I have a Spixi in with my Metallics (as well as a couple of Amanos and some CRS), they are a trio of males however and the tank is approx 30L, but they're so active it's insane! They'll be getting a 60L maybe when I move with a few more buddies.

I'm sure I can pick up a 50L cheap somewhere if I manage with the whole salt thing, which I haven't ever done and am studying the faq in your signature!! The 25L was going to be a Sulawesi shrimp project, but they're so hard to get hold of and so expensive, I'll put that on hold until they're more available.

And I'm glad to see Hygrophilia works in brackish as I have HEAPS of it.

 

[nmonks]

Almost any plant happy in hard water will be happy in low end brackish (SG 1.003 or less). Brackish water tanks are actually very easy to keep, and because the marine salt mix steadies the pH and the sodium chloride detoxifies nitrite and nitrate, they're actually less prone to problems that freshwater tanks.

Enjoy the FAQ!

Cheers, Neale

 

[Jonathangerous]

If I recall correctly, Pou collected the fish which would eventually be bred into picta red in freshwater. That said, I would not generalize so far as to say mollies are primarily freshwater fish, etc. Such assertions should be observed on a species, or even populational level. For example, p. latipinna is found in all manners of salinities, and I myself have found them particularly common in the panhandle region (introduced of course) in higher end brackish.

Limia are often touted as brackish water fish due to the idea that they are, as de novo Antillian freshwater residents, that they were initial seagoers. This may be true, but it should be noted that many species are freshwater exclusive, if not skewed (best illustrated in Haney et al, 2003).

Also, just out of curiosity, what is the method of action for salt mediated nitrate detoxification? I've heard this touted before--not saying it doesn't exist.

 

[nmonks]

If I recall correctly, Pou collected the fish which would eventually be bred into picta red in freshwater.

The specimens I saw at Wildwoods weren't any particular variety, but wild-type fish. Keith is pretty good at sourcing wild-caught fish.

That said, I would not generalize so far as to say mollies are primarily freshwater fish, etc. Such assertions should be observed on a species, or even populational level. For example, p. latipinna is found in all manners of salinities, and I myself have found them particularly common in the panhandle region (introduced of course) in higher end brackish.

I went through this over and over with the editors at TFH while putting together my brackish book. Essentially, mollies are common in both freshwater and brackish water habitats. They are rarely found in their natural range far from the sea, but they have been established outside their natural range far inland, e.g., in California and Arizona. So, brackish water doesn't seem to be necessary for their success. But having said that, most experienced aquarists agree that mollies are easier to keep in slightly brackish water. Yes, you can keep them in freshwater aquaria, but it's easier not to. The reasons for this are obscure.

Also, just out of curiosity, what is the method of action for salt mediated nitrate detoxification? I've heard this touted before--not saying it doesn't exist.

It's from publications like the Interpet Manual of Fish Health. The authors presumably extrapolated from lab work that nitrate toxicity (i.e., how much is needed to harm/kill) decreases as salinity rises. If you accept mollies are nitrate sensitive (as seems to be the case) upping the salinity means that they will tolerate higher levels of nitrate than otherwise.

Cheers, Neale

 

[Jonathangerous]

Oh, I see. This thread is referring to picta in general.

"So, brackish water doesn't seem to be necessary for their success."

I totally agree, which is why population to population characterizing is more apt, imo. Take another common molly type poecilid, p. sphenops. There are naturally occurring freshwater exclusive populations. I would argue that those should be kept exclusively in freshwater, as per their life histories.

 

[nmonks]

I'm not convinced there are salt and freshwater "populations" -- which in biology means a specific thing: a more or less isolated group of individuals with distinctive genetics of their own. The specimens established around the world in freshwater rivers are the usual aquarium trade mishmash, not descendants of one particular regional variant. Having said that, I do accept that for Poecilia sphenops and Poecilia mexicana there are very distinctive populations known; with the former a sulphur-tolerant cave-dwelling form and with the latter another cave-dwelling form with smaller eyes (if I recall correctly).

The stuff in the trade are all hybrids to some degree, so talk of populations is even more meaningless. This is the point I keep trying to make. It's not what molly species X prefers in the wild, or originally came from, that matters. This is a purely practical issue. In aquaria, for whatever reason, mollies are more likely to do well in slightly brackish water than plain freshwater. Is it because aquarists keep them too cool, so their immune systems don't work? Does marine salt mix stabilise pH and provide the carbonate hardness required? Does sodium chloride detoxify nitrate? All these ideas have been proposed. Very obviously they don't matter in the wild, since populations of both wild and feral mollies seem to do just fine in freshwater habitats.

I'm not arguing you cannot keep mollies in freshwater. But I do argue that casual aquarists (the sorts likely to ignore pH, water hardness, and water quality to some degree) will do better if they keep their mollies in slightly brackish water conditions. To me, it's a no-brainer. The requisite amount of marine salt mix is very inexpensive, and since it automatically sets the right pH and hardness level, it's about the easiest way to provide optimal conditions for maintenance of these fish. Maybe not the best way, but certainly the easiest way.

Cheers, Neale

 

[Jonathangerous]

'I'm not convinced there are salt and freshwater "populations" '

"A Cavernicolous Form of the Poeciliid Fish Poecilia sphenops from Tabasco, Mexico "...published in Copeia, so you know it's legitimate. I believe you already referred to this, yet these are freshwater exclusive (mexicana and sphenops are somewhat interchangeable since the name basically nonspecifically refers to an entire complex of "species").


"The stuff in the trade are all hybrids to some degree, so talk of populations is even more meaningless."

Not at all true, especially not for wilds such as picta. And given that this is in the rarer livebearers section, it is far more relevant than talking about balloon mollies and the like. Being a wild type enthusiast I was always schooled in the habit of finding out where your fish is from, and matching your water to reflect that of the natural habitat, especially in goodeids, where locale to locale parameters differ significantly.

My main point is that for wild fish, it is never best to generalize about water preferences to classify an entire group of fish--"molly" refers to at least 25 species of fish, not all of which share the same habitat preferences.

 

[nmonks]

"A Cavernicolous Form of the Poeciliid Fish Poecilia sphenops from Tabasco, Mexico "...published in Copeia, so you know it's legitimate. I believe you already referred to this, yet these are freshwater exclusive (mexicana and sphenops are somewhat interchangeable since the name basically nonspecifically refers to an entire complex of "species").

I just said this! Honestly, I do know about the wild populations within these species. My background is actually systematics, albeit palaeontology rather than biology, and I do understand about species, and in fact have named a few in my time. You have to be careful about putting all your faith in one paper, even very good ones: the differences between several distinct populations on the one hand and one variable species on the other is often arbitrary, and can have little or nothing to do with how the animals themselves work.

But again, just to be crystal clear, we're talking about the pet mollies being sold in pet stores. Black mollies, chocolate sailfin mollies, and so on. Much as I'd like to believe that these were true species, albeit in man-made coloured varieties, I don't think that's very likely.

I've never seen any of the cave-dwelling populations of Poecilia in the trade, so they're largely irrelevant to this discussion (which is, to be fair, wildly off-topic now). I'd certainly love to keep them, and hope they do turn up eventually. But thus far, I've never seen them.

"The stuff in the trade are all hybrids to some degree, so talk of populations is even more meaningless."
Not at all true, especially not for wilds such as picta. And given that this is in the rarer livebearers section, it is far more relevant than talking about balloon mollies and the like. Being a wild type enthusiast I was always schooled in the habit of finding out where your fish is from, and matching your water to reflect that of the natural habitat, especially in goodeids, where locale to locale parameters differ significantly.

Again, I was talking about the farmed mollies sold in the pet trade and purchased by the million. Not the occasional batch of wild-caught fish your or I find most attractive. Like you, I far prefer wild-type fish, and the livebearers I happen to have (Limia, Ameca splendens, and some sort of Nomorhamphus halfbeak) are all wild-type, if not necessarily wild-caught.

My main point is that for wild fish, it is never best to generalize about water preferences to classify an entire group of fish--"molly" refers to at least 25 species of fish, not all of which share the same habitat preferences.

Oh, I agree, I wouldn't pretend to say that all Poecilia prefer brackish water, though I doubt any are harmed by it. Indeed, given the choice between soft water and brackish water, I dare say most if not all would do better in brackish water. Similarly, if you're dealing with high levels of nitrate out of the tap (e.g., up to 50 mg/l here in Southern England) then brackish water may be advantageous, even with species that do not normally come from brackish water habitats.

But when it comes to the 99.99% of the mollies sold and kept in the hobby, i.e., the various Poecilia hybrids, then slightly brackish water remains a good way to keep them, if not necessarily the ideal.

Cheers, Neale

 

[dunchp]

Fantastic 'off topic' discussions guys, it is obvious that you both know what you are talking about but fishkeeping is a bit like the story of the elephant and the blind men, it all looks different depending upon where abouts you are standing (or words to that effect).

I just thought I could let you know that the BLA magazine has featured articles on Cave Dwelling Poecilia Mexicana (which will almost certainly never be seen in aquaria as they are kind of ugly), habitats of mollies and various other articles contributed by scientists and hobbyists alike. It is well worth the £16 for a years subscription, even if I say so myself.

I am not aware of the sulphur tolerant Poecilia sphenops (although that doesn't mean that they do not exist); the sulphur tolerant species is Poecilia sulphuraria and a strain of mexicana (again we have had articles on sulphuraria in the recent past too).

If you want to research natural habitats, use the Neodat resource at www.neodat.org which is a pretty good font of knowledge.

 

[OldMan47]

The sulfur tolerant P mexicana were a subject of a very good lecture at last spring's ALA convention. There has been quite a bit of work done on them and there are differences in the shape of their mouth compared to the same mollies from only a few KM away in the same waterway. It seems that the water has caused the mollies that actually live in that water to have their mouth form so that they can take advantage of the small area at the top of the water that actually has some oxygen content, compared to the deeper parts of the water. After leaving the fish in an aquarium for a time, the mouth shape returned to a more normal shape for P mexicana. I probably missed some of the details but it was a fascinating lecture at the time.

 

[dunchp]

Yup, Michi Toebler (one of the scientists responsible for the research) wrote an article for the BLA which Practical Fishkeeping Magazine used in June 2008 so there are a few photos of the fish in the June 2008 edition of the PFK magazine. The research itself was about the cave dwelling species, but it compared them with the same species from surface dwelling, sulphurous habitats and normal habitats. The research looked at how the species adapted to take advantage of a habitat with two natural challenges (sulphurous water and lack of light), it was very interesting.

Way, way off topic now though