I’ve been working with Vietnamese Mossy frogs since around 2001, they are great frogs and easy to keep, however there are a few tricks to succeeding with them.  Please check out this article I wrote on them for Reptiles Magazine, back around 2010.  You can find it here- https://dartfrogsandgeckos.com/f-a-q-dart-frog-care-sheets/information-dart-frog-feeding-care-and-terrarium-setup/keeping-and-breeding-vietnamese-mossy-frogs/

Meanwhile, checkout the below discussion of some of the history of these frogs in the hobby, as well as tips on raising tadpoles to produce females.

The First Mossy Frogs in the US

I first became aware of these frogs back in the mid 90s.  In those days, you would call breeders or dealers and get put on their mailing list. Then, one day you would open your mail box and find a folded paper pricelist, or perhaps a shiny card stock folded flier.  These were always a great find, and of course read through carefully to see what was available. The price list with the Mossy frogs was offering them for $400 each. Honestly that isn’t a bad price, although I suspect that probably equals something more like $1500 now. 

The flier had a line drawing of them, and it just looked amazing, all spikey! At that point in time, frogs were not my focus, and spending a couple of thousand on a group of four or five of them just wasn’t a thing I was going to do. Anyway, apparently that shipment must not have had both sexes, or perhaps they died, I don’t know, I never saw them again.

A few years later, about 2001, a dealer I had previously dealt with offered me a shipment of 20 “farm raised” Mossy frogs. These were supposedly from Thailand, and all adults.  I don’t recall exactly what the price was, but it was around $200, and I decided to buy all of them. This turned out to be a great decision, I did well with them, they bred easily and were generally all around easy to keep. Of course the offspring sold well…that always helps.

So Many Males!

It wasn’t long before there were a couple of other breeders working with them, and it also wasn’t long before I began hearing a story from person after person…”Hey, got any female Mossy frogs? I bought (fill in any number from 4 to 25) and they all turned out to be males”. (To be clear, these were frogs they had bought from other breeders, sometimes in the US, sometimes imported from Europe) I’d add that by this time I had noticed that while most of my customers did wind up with females, it was generally only one out of four or so.

Before long, trying to obtain a female Mossy frog had become somewhat of a “Holy Grail” kind of search, and over the years, and up till today,  I would say that a female mossy frog is one of the most sought after frogs, and also one of the most commonly misrepresented frogs. I can’t imagine how many males have been sold as females.

Temperature Sex Determined Frogs?

Probably around 2010 or so, I found some Russian research papers on mossy frogs that suggested that they were temperature sex determined.  Of course, by that time it was already sort of a given, but still it helped to point breeders like me towards keeping tadpoles at cooler temps.

Overall, though, many questions still remain, since no one that I know of has produced even a majority of females, much less 100% females.

The recipe for producing a male Vietnamese Mossy frog is simple…keep your tadpoles in water that is at around 74 to 76 degrees, and every single one will be a male.  Just a few degrees cooler, say 71 to 73, and you will get maybe around 20 to 30 percent females.  Personally, I’ve tried raising tadpoles at colder temps, into the lower sixties. However, at temps below roughly 65, development slows considerably, and losses increase.  I’ve raised tadpoles in the upper sixties, and still produced males, although I haven’t kept very good records on this.

My suggestions for those of you who want to breed these and produce a decent mix of males and females is to raise the tadpoles at water temperatures around 68- 70 degrees.  As the tadpoles get closer to morphing out, it is safe to raise the water temps to around 74. This will speed development, and as long as they have begun to develop their back legs, gender is set.

Anyway, as with many other frogs, Mossy frogs seem to ride a wave of popularity. They fluctuate between being highly sought after, to being fairly easily available. Regardless of whether they are common or rare, they make a great display specimen, and are fascinating to breed.