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Loh Kwek Leong 
Title:  Mosses and the Men Who Love Them

Summary: Identification of aquarium mosses is, surprisingly, not as straightforward as most people believe. They can reproduce themselves sexually by means of capsules. In Singapore, Java mosses do not appear to produce capsules. Why? - or do they? Illustrated.
Contact for editing purposes:
email: Loh "Timebomb" at:

Date first published:  2004
Publication:   and Loh's web site

Reprinted from Aquarticles:
November 2005: Fins & Friends, Regina Aquarium Society
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Mosses and the Men Who Love Them

by Loh Kwek Leong  of Singapore
Visit Loh's for information on killifish keeping.

Hi, folks. Before you read on, be prepared for a few surprises. As I said in a recent forum discussion - What we thought we knew, we were way off the mark. What we didn't know; the answers were staring at us all the time.

First surprise - Java Moss, of which we all (or maybe it was only me) thought the identity was never in doubt - In publications everywhere and all over the internet, the scientific name of Java Moss has always been Vesicularia dubyana. Right? Well, we were all wrong. Java Moss, according to Dr Tan is a species of Taxiphyllum. That's the genus name and for a very strange reason which I will go into details later, Dr Tan cannot confirm the species name. Here's a pic of Java Moss:

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Second surprise - Taiwan Moss and Christmas Moss are mosses that belong to different genera. In other words, although they look like they are the same plant, they actually belong to different groups. You may be surprised, just as I was, that as far as identifying mosses are concerned, looks count for little. The way Dr Tan goes about identifying the mosses, heck, he doesn't even pay attention to the shapes of the fronds. How they grow in our tanks, whether upright or hanging down, count for even less. Dr Tan goes deep down into the cellular level; he looks at the structure of the cells under a powerful microscope. The sizes and shapes of the cells are an indication of genus. To confirm the species, he has to look at the spores. We (Gan Cheong Weei, Kim Cheng, Choy Heng Wah and I) had a wonderful time peering into Dr Tan's microscopes. They opened up a whole new world for us. We saw things like rhizoids (mosses' roots), sexual organs, cells and things like double costa (midriff of mosses). Here are pics of the Taiwan and Christmas Moss:

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Third surprise - Erect Moss which we all thought were very different from Christmas as it grows up instead of down. Well, it belongs to the same genus as Christmas and here's the shocker - the genus is Vesicularia!! If you are surprised, you can imagine how I felt when Dr Tan informed us about that. To know now that Christmas and Erect moss are species of Vesicularia and to find out that what we thought (Java Moss) to be Vesicularia dubyana was actually another plant instead, heck, I'm still reeling in shock over all this. I can't reveal the species names of the Christmas and Erect here because Dr Tan said he cannot confirm them yet. Here's a pic of the Erect Moss:

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Fourth surprise - Willow Moss, scientific name Fontinalis antipyretica. No mix-up about the common and scientific name of this plant but what we thought to be Willow Moss is actually Java Moss in disguise I brought some for Dr Tan to examine and he said what I had were Java Moss. I'm inclined to believe that many of the so-called Willow Mosses sold in some fish shops in Singapore are also actually Java Mosses. Dr Tan said Willow Moss is not native to the regions around here.

Fifth surprise - There's a species of Vesicularia growing all over the place in Singapore. I found some at the foot of Telok Blangah Hill Park. Here's a pic:

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I won't reveal the name of this Vesicularia as the species name isn't confirmed but all species of Vesicularia, of which there are 4, are, according to Dr Tan, semi-aquatic mosses. In other words, they can be grown submersed in our tanks. Is this great news or what!!! I would encourage all of you to look harder at the grass patches around your housing estates. There’s a very good chance you can find this moss everywhere. Find them and grow some in your tank but be mindful not to destroy the habitats where they are found. Take only what is necessary and please ensure there’s enough of them left for the moss to propagate.

Speaking of propagation, I will explain why Dr Tan cannot confirm the species name of the Taxiphyllum sp, the moss formerly known as Vesicularia dubyana. (You know, for some strange reason, I got helluva kick when I typed that last phrase ). Please take note that my explanation may be somewhat fuzzy as I’m just regurgitating what Dr Tan told us.

Mosses can reproduce themselves sexually. They have male and female sexual organs which cannot be seen by the naked eye but are very distinct under a microscope. Male organs release sperm cells which find their way into the female organs and fertilise the eggs inside. Once fertilised, the female organ transforms into a thing called a capsule. If you have many capsules growing in your mosses, it would mean there's a lot of wild sex taking place in your tank. Here’s a pic of two Christmas Moss capsules:

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The one on the left shows a complete capsule. The one on the right is a capsule that has released its spores. Spores are like seeds. Wherever they land, new mosses will grow. In their natural habitats, winds carry the spores of terrestrial mosses. Under water, the current carries the spores of aquatic mosses down the streams where they live. Don't ask me why we don't see Christmas mosses sprouting all over our tanks but I have some mosses growing from the corners of my fish tank and I can tell you sure as hell I didn't plant any moss there. Here's how they look growing on the silicone:

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For some strange reason which even Dr Tan couldn’t explain, all the Java Mosses found locally do not produce capsules. It could be something to do with the chemistry of our water but Dr Tan isn’t sure. To confirm the species name, Dr Tan has to be able to see the spores. Without capsules, there are no spores. There’s a species of Java Moss from Vietnam that produces capsules but unfortunately, Dr Tan didn’t have a live specimen. He suspects that the Java Moss from Vietnam is the same as those found locally but without spores, this cannot be confirmed.

I’m appealing to all of you, on Dr Tan’s behalf, to take a close look at the Java Mosses in your tanks. If you find even just one capsule, it would be worth a great deal to scientific research. Let me know and I will be at your house as soon as I can to pick up that capsule for Dr Tan. But please make sure it’s from Java Moss and not any other mosses. I personally have grown Java Moss for many years but have never seen a capsule among them before. It could be the capsules will only appear when Java Mosses are grown emersed or when they are dosed with hormones. Neither Dr Tan nor I are sure about this but grow them emersed, submersed, whatever-mersed; dose them with fertilisers or hormones; pee into the tank if you have to: if you can produce one capsule from your Java Moss, you could very well become famous overnight. Your name may go down in the annals of scientific research .

On my way home from Dr Tan’s lab, I stopped at two fish shops to buy more mosses. Here are the pics:

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The fish shop owners whom I bought the above mosses from said they were Willow Moss and Taiwan Moss respectively. I'm quite sure they are, as we were, wrong about the names. I'll be sending these mosses to Dr Tan for proper identification later.

Dr Tan is just as fascinated of our love of aquatic mosses as we are intrigued about their scientific names. The more mosses we can give to him, the better we will understand these lovely plants. If you have some special moss in your tank with scientific name unknown, I appeal to you to send some to me and I will give it to Dr Tan. In exchange, I will give you the mosses (Christmas, Erect and Java) I have in my tanks. Thank you.

In closing, I would like to thank Gan Cheong Weei for setting up the meeting with Dr Benito Tan. If it had not been for Gan, we would never have met the expert.