November 01, 2018

The attributes we ascribe to leaves...Myth, reality, or somewhere in between?

Some three years in to our mission of elevating the use of botanical materials in aquariums here at Tannin Aquatics, and we are starting to see some of the "haze" clear about their usage and benefits.

Hyperbole and rhetoric are starting to fade a bit under the objective reality that arises when we start gathering personal experience, as opposed to simply regurgitating the speculation of others.

With more and more hobbyists playing with botanicals in all sorts of aquariums, we're seeing real tangible aesthetic and functional results, including pics of amazing "leaf-centric" scapes, and lots of stories of fishes spawning shortly after the use of leaves commenced in their aquarium.

Let's give 'em "props!" Leaves are amazing when utilized in aquariums.

However, it seems to me that, over the years, a lot of "capabilities" are ascribed to them- some of which are legit, and others likely still simply conjecture.

Yes. That's me- the botanical vendor, saying this. Nothing new, though.

Catappa is the biggest "superhero" among leaves in this regard.

There are a lot of spectacular claims attributed to these leaves, and it’s often hard to sort through all of the hyperbole and find the potentially true facts that might be of interest and value to us as aquarists.

The last thing I wanted to do when I started Tannin Aquatics was to get caught up in touting all sorts of unsubstantiated claims about these leaves and the substances they contain, so I did my best to ferret out just what the ”real deal" is here! None of this is the definitive word on the subject, but it was helpful for me to at least try to extract some practical information out of the many claims about these leaves.

For many years, Betta breeders and other enthusiasts in Southeast Asia added catappa leaves to the tanks and containers that held their fishes, and noticed a lot of positives…Those who actually fought their fishes seemed to feel that, when they were kept in water into which catappa had been steeped, their fishes recovered more quickly from their injuries.

Those who simply kept various species of these fishes (not for “blood sport”) noticed increased overall vigor, appetite, and health among their fishes.

And there IS some legit science behind at least some of these claims: The bark and particularly, the leaves of the Indian Almond tree (Terminalia catappa)- contain a host of interesting chemicals that may, indeed provide direct health benefits for tropical fishes. The leaves themselves contain several flavonoids, like kaempferol and quercetin, a number of tannins, like punicalin and punicalagin, as well as a suite of saponins and phytosterols. Extracts of T. catappa have shown some effectiveness against some bacteria, specifically, Plasmodium, and some parasites as well.

I found a study conducted by fisheries researchers in Thailand on Tilapia, which concluded that Catappa extract was useful at eradicating the nasty exoparasite, Trichodina, and the growth of a couple of strains of Aeromonas hydrophila was also inhibited by dosing Catappa leaf extract! In addition, this solution was shown to reduce the fungal infection in Tilapia eggs:

(Chitmanat, C., Tongdonmuan, K., Khanom, P., Pachontis, P. and Nunsong, W. (2005). Antiparasitic, Antibacterial, and Antifungal activities Derived from a Terminalia catappa solution against some Tilapia (Oreochromis niloticus) Pathogens. Acta Hortic. 678, 179-182 DOI: 10.17660/ActaHortic.2005.678.25)

Boom! 💥

Okay, that makes sense!

Now, we find many similar attributes applied to other leaves, such as guava, Magnolia, and even Loquat. For example, Magnolia leaves produce phenolic antimicrobial chemicals, compounds called coumarins and sesquiterpene lactones, which discourage predation and grazing by terrestrial insects. Coumarins have known anti fungal properties.

Does it apply to fishes and shrimp?

Most leaves contain significant complex sugars (polysaccharides), which can directly benefit these animals when consumed. I mean, who doesn't get a little "kick" from complex sugars, right? 😆

Much is still anecdotal for aquarium use- perhaps even a "forced fit" based on the known benefits of these compounds for human health...And much remains to be discovered about their benefits for aquatic use. I mean, just because the compounds they contain provide specific benefits for people is no guarantee that they will be absorbed and utilized by our Neocaridina, right?

Help, physiologists out there!

I mean, there is a literal "cottage industry" surrounding the use of various leaves and botanicals expressly for the purpose of "treating" and "conditioning" shrimp. And look, I'm not knocking this. We have plenty of customers who have used various leaves and even botanicals, for years, and strongly believe that the use of leaves plays an important role in the success they enjoy with these animals.

I am just a bit curious, of course, as to which substances are absorbed from leaves by these organisms, and whether or not the benefits that come to humans from the use of the leaves applies here. We'll continue to objectively present some of these "hypotheticals" ascribed to leaves for hobbyists to research and examine.

Now, one thing that we do know is that shrimp (and some fishes) consume leaves- and they also consume the biofilms and fungal growths which occur on the surfaces of the leaves. This is a fact, observed daily for decades in aquariums all over the world. What specific benefits are they garnering as a result?

And of course, we can go on and on about the humic substances and tannins which are released by leaves and botanicals directly into the aquatic environment. That's a legitimate, known "thing", documented by a lot of scientific study.

And of course, we love the aesthetics provided by leaves when used in our 'scapes. They provide a unique, natural look, tinted water, and support a complex web of life forms in the aquarium- just like they do in nature. We'll keep pushing that as a terrific "benefit!"

And, with the ever-increasing availability of leaves and botanicals in the hobby, it's never been easier for us fish geeks to experiment, explore, and work with leaves in a variety of situations.

We're nowhere close to having all the answers on the benefits ascribed to leaves, but continued effort by you- our informed worldwide community- will no doubt get us further along the road to unraveling the myth- and reality- of their capabilities.

Stay open-minded. Stay curious. Stay consistent. Stay engaged...

And Stay Wet.

Scott Fellman

Tannin Aquatics