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Biofilms and those who love them...

Tannin Aquatics

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Are you one of the many hobbyists who has decided to make that jump into a new and different direction by creating a botanical-influenced aquarium?

If so, not only are you cool (yeah, I think you are), but you are now probably becoming familiar with the good, the bad, and the annoying aspects of "New Botanical"-style systems.


Today, let's focus on one of the more annoying aspects of these types of systems; something that, despite the "mental jump" we've made to this extremely different and very natural aesthetic, still gets on our nerves at times: Biofilm!


Even the name, "biofilm" conjures up imagery of some sort of gooey, smothering, and altogether unattractive stuff, which can wreak havoc with the aesthetics of your carefully planned botanical-influenced aquarium for all but the most hardcore of us "NewBo" lovers.

Now, as shrimp lovers, you're more than appreciative of them. We know that biofilms have many desirable benefits for shrimp. In fact, I recall a thread on this very forum a year or two ago, in which members were trying to find out what the best ways to recruit biofilms for their shrimp tanks was. THAT is love, my friends! Of course, in a larger-scale "community tank" situation, they can be considered by many to be an aesthetic distraction. So, this piece is taking a more generalized approach, and you can hopefully understand the perception about and issues caused by biofilms for many hobbyists...

Let's state it again for the record (for the "umpteenth" time, too...)...These are not harmful, and are a perfectly natural thing.  In fact, they're downright useful, as these are conglomerations of useful bacteria, whose "sticky" surfaces build into this matrix.  However, our aesthetic sensibility as aquarium hobbyists has long ago deemed such growths as unsightly and undesirable, and, hey- I'll give you that- too much of this stuff is nasty to look at. It is, however, very, very common in rivers and streams throughout the tropical world, as you'll see if you observe any of the underwater videos and pictures on the internet of these environments.


Without revisiting what exactly these biofilms are (we've done that in a previous edition of this blog), lets just summarize that the most common biofilms we see consist of bacterial assemblages of organic material, sugars, some algae, and even fungi of various sorts. A veritable smorgasbord for aquatic animals, really.

Most common on pods and leaves are the bacterial biofilms, which, in my experience, are the most transient. They tend to ""bloom and bust" in relatively short spans of time (although it can seem like an eternity if you despise the stuff and are waiting for it to go away!).

Next are fungi, which tend to be really common on wood and pods, because these are terrestrial materials which contain significant organic materials and offer a great substrate for these organisms to grow on. You see it often on various sorts of driftwood, and it has long been the bane of many hobbyists existence! They are at times maddeningly tenacious.


Less common still (especially in relatively new aquariums) are algae, particularly filamentous varieties, such as the hated "Black Beard Algae", followed by various cyanobacteria, diatoms, and others. These tend to be nutrient-limited, and typically are brought under control through various husbandry adjustments, including use of chemical filtration media (activated carbon, etc.), stepped-up water changes with high-quality (RO/DI) water, careful feeding, stocking, and of course, physical removal.

Without delving into the control of nuisance algae and other growths, let's take a very brief, by no means comprehensive, look at some of the "biological controls" (i.e.; fishes and invertebrates) which can assist us in controlling excessive amounts of these unsightly growths in our botanical-laden systems. Keep in mind that this is not intended to be a definitive guide or a guarantee that any of these animals will do the job. I'm basing this on personal experiences that I've had, as well as other hobbyists who work with these kinds of systems:

Otocinculus catfishes- These little fishes are well-known for their love of algae. They are also known for starving to death in aquaria if they cannot find enough. I've seen "Otos" consume massive quantities of algae, and then turn their attention to biofilms. Now, they're probably going after the algal growths that are commonly bound up in biofilms, but their wrapping actions do help to dislodge the material from the surfaces they adhere to. So, all-in-all, they are more of an incidental biofilm grazer, IMHO.


Twig Cats (Farlowella sp.)- As above. These fishes are also known to be rather "compilation" in their nutrition habits; truly being algae consumers, with a little animal and other organic material being consumed from time to time. Do not purchase one of these animals with the expectation that it will demolish your biofilm "issue." Rather, add one of these interesting, endearing, long-lived (under the proper circumstances) fishes because you want one for the long term, and enjoy the "side benefit" of them occasionally jumping on some biofilms.


Loricariid catfishes- If ever there was a genus who's members were all over the map, in terms of dietary preferences and habits, this one could be it! As with the species above, the are not "scavengers", and should never, ever, EVER be purchased as "cleaning" fishes, an absurd and antiquated notion that has killed many hapless fishes over the years. Many species will eat some vegetable and animal matter that they encounter between feedings of prepared foods, and their consumption of biofilms is very much incidental at best. Nonetheless, I have seen several species of HypancistrusPlecostomus, and even my Peckoltia occasionally grazing deliberately on biofilms in my aquaria and those of others.  


Amano and other "ornamental" Shrimp (CaridinaNeocaridina, etc.)- These are probably the one "exception" of animals on this list, in that they specifically may feed on biofilms as a large part of their diet. These little shrimp are interesting and popular for many reason, and they have that added attraction of being biofilm lovers! Now, like any animal we add when with our own agenda, they cannot be expected to rid your entire aquarium of biofilm. They are, however, superb consumers if this material, and will also aid in the consumption of decomposing leaves and the softer botanicals as well. If their other needs are met (including not having predators in the tank!), they can indeed be counted on to have some impact on biofilm. And, with at least one species hailing from Amazonia, one could conceivably have a semi-biotopic-snob-acceptable facsimile of nature...arrghhh.


Pencilfishes- Huh? Really? Yeah! I've kept a wide variety of Pencilfishes, and they seem to spend a large amount of time picking at biofilm and other material adhering to botanicals, and specifically, wood. Currently, I'm working with N. beckfordi, and they engage in this activity almost constantly throughout the day (between feedings, of course!). I am convinced that they are not specifically targeting the biofilm directly; rather, I think that they're looking for tiny crustaceans and other life forms that live in the matrix. Nonetheless, their picking distrubs the films and puts it into suspension, where it can more easily be removed by filtration. This was an unexpected "plus" of this most beloved group of fishes. Now, I must warn you, you shouldn't even consider Pencilfishes as a biofilm "control mechanism", but the collateral benefit is nice.


Headstanders- As above, although these guys are more widely known as consumers of 'aufwuchs", and include biofilms and filamentous algae as a considerable part of their diet. They can attain a fair size, and some are not the best fishes for a peaceful community aquarium. Nonetheless, I had a group of Chilodus punctatus (Spotted Headstander) that were quite adept at eating the stuff.


And of course, there is always manual removal...you know, siphon, soft-bristle brush...that sort of thing. This is more of a "band aid", and will require frequent repetition, but occasionally, you will see a successful eradication of biofilms caused by human intervention...

In the end, the most effective strategy for dealing with biofilms consists largely of patience. It's all about understanding what is going on, and appreciating what biofilms are, and understanding that they are not harmful. That being said, the aesthetic downside to biofilms definitely makes looking at strategies to keep them in check important for anyone working with botanical-influenced aquariums.

I hoep this little round-up of some of my fave "biological controls" for dealing with biofilms gives you some ideas, inspiration, and perhaps, a little basis for further discussion!

Stay engaged. Stay enthusiastic. Stay patient.

And Stay Wet!

Scott Fellman

Tannin Aquatics

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