When good botanicals go bad...just a phase?

So what happens after you place your botanicals into your aquarium?

I mean, what can you expect? Well, a few things. First of all, if you've properly prepared them as per our "Aquatic Botanical Preparation" page, you'll expect them to pretty much sink right to the bottom.

All good.

Well, occasionally, you'll get one or two that refuse to "give up", and rise to the surface. What do you do?

A couple of options here: Best is to remove the "offender" and soak it in some boiling water for about 20 minutes. That typically does the trick. Or, you can leave it overnight or longer in a container of room temperature fresh water, continuing the process you began some time back.

The more serious concern most people have is what to do when they see yucky "biofilms" start taking over their botanicals after placement in their tanks. This doesn't happen in every aquarium, but it happens often enough that we have to view it as a sort of "phase" that our systems go through when utilizing aquatic botanicals, much as we endure as reefers with nasty algae blooms over our freshly set-up live rock and sand.

I'm reminded of the expression that we use in reef keeping a lot to describe algae issues: "Algae will opportunistically colonize undefended substrates that provide a suitable growing surface."

So, same thing with botanicals. The biofilms will arise relatively quickly on some botanicals, forming unsightly, stringy/gooey "snot" that looks like it's gonna take over the tank.

What do you do?

First off, don't panic.


This is a natural occurrence; bacteria and other microorganisms taking advantage of a perfect substrate upon which to grow and reproduce. Freshly added botanicals offer a "mother load"of organic material for these biofilms to propagate, and that's occasionally what happens - just like in nature.

Of course, an aquarium is not a tropical stream or lake, and you don't want to see a tankful of snot! Not to worry.

First off, take comfort in the fact that this is sort of a passing phase, and can take anywhere from a few days to 2-3 weeks before it subsides. During that time, there are some actions you can take besides cursing the whole idea of throwing aquatic botanicals in your system in the first place!

  • You can wait it out. That's right. Do nothing, except appreciate the wonders of nature, no matter how unsightly they may be at times. I mean, didn't nature make the "Death Flower" and the "Slime Mold" Yeah.


  • You can remove the offending botanicals, give them a good scrub with a soft bristle brush (like an old toothbrush), a rinse in fresh water, and put 'em back in.


  • You can remove the botanicals, give them a good scrub, and re-boil/soak them again. Although a bit redundant, this does have the advantage of removing some of the trapped organics that lead to the initial "outbreak", but you may see it happen again.


  • You can leave the botanicals in place, and employ some natural control, in the form of ornamental shrimp. Yeah, that's right- your "Crystal Red Shrimp", "Bee Shrimp", and the rest absolutely adore biofilms, and will attack it voraciously. Alternatively, we've learned that some fishes, like Plecos, some Corydoras cats, and even Leporinus and other "Headstanders" seem to pick at this stuff fairly aggressively.


Obviously, the important thing to remember here is not to panic, and make rash decisions, tossing away everything. The only reason I'd toss away a botanical is if it takes on that yucky "hydrogen sulfide" (rotten egg ) smell. This doesn't happen in every situation. You'll occasionally get a seed pod or other botanical that will get that smelly, mushy thing going on...toss it.

Remember, even the most durable pods and leaf-like botanicals will soften up after preparation and prolonged submergence. That's what happens in nature, too. That's why leaf litter contributes to the richness of the aquatic environment, fostering the growth of microorganisms that serve as food for fish fry, and benthic creatures that provide foraging opportunities for adult fishes, like dwarf cichlids, catfishes, and even Tetras, some Bettas, and Killifish.

One interesting phenomenon that I've noticed: When botanicals are added to a system that already has the influence of humic substances and tannins, such as in the case of a system where you've added Catappa leaves or bark- the incidence of this biofilm occurring in significant amounts is rather uncommon.

I think- and notice I say "I think"- that the reason might be the alleged anti-microbial properties that these leaves appear to possess, perhaps to some degree limiting the excessive growth of bacteria. Remember, this is just a theory I'm tossing out, based on purely anecdotal observation from myself and others who play with botanicals, and the science behind this may be in conflict with the theory. Regardless, it's something I've noticed. 

Take away- perhaps it's not a bad idea to throw in your Catappa leaves, bark, etc. first- or at least, concurrently with the other botanicals, to test out this theory.

Of course, there may be so many other factors involved, such as the "maturity" of the aquarium in question, or the pH, alkalinity, etc. of the water- lots of potential variables to consider. 

Regardless of what course of action-if any- you choose to take to address the "biofilm phase", should it occur in your tank- the key takeaway here is not to panic. Like so many things in aquarium keeping, we need to understand what's actually going on before jumping to conclusions. When you understand that what's going on is just part of the natural cycle, you'll perhaps be able to take a bit of comfort knowing that this little "right of passage" you are experiencing is a transient thing- part of the dynamic processes that occur when wood, leaves, water, and life interact.

As this is a relatively new practice, we still have much to learn. Feel free to share your experiences, theories, and observations, so that we may all benefit!

Stay engaged. Stay calm.

And stay wet.


Scott Fellman

Tannin Aquatics

Scott Fellman
Scott Fellman


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