Trashing the "scavenger" stereotype!

Perhaps you're just like tend to analyze everything in this hobby!

I freely admit that I can be easily annoyed at times. And it's kind of funny what kind of stuff discussed in our hobby can just set me off. It typically happens when I am scouring aquarium forums ( as is part of my daily ritual) and come across some sort of discussion that demonstrates the strange indifferences we tend to demonstrate towards aquatic animals at times.

I came a cross a few discussions in which new aquarists were asking the age-old questions, "What are the best fishes to eat algae and keep my tank clean?" and "What's a good 'cleanup crew' for my community tank?"

Innocent enough, right? I mean, not really a big deal, huh?


This is a question that, in my fiesty, ripe old age, makes me a little bit concerned, actually. In fact, it kind of gets me pissed off a bit. Yeah. I mean, there should be a lot of other things about this hobby that get under my skin, but this one sort of does it for some reason. I mean, here we are in the 21st century, with every technological advantage possible- devices, techniques, and methodologies designed to maintain pristine water quality and beautiful aquariums, and we're still sort of "deferring" the maintenance duties to fishes and other animals...? 

(Peckolitia compta L134- Just an "algae eater?" I should think not!)

Makes you think a bit. 

I think we lean a bit too much on various animals to perform some of the "roles" that we need to have a better grasp of...This is in stark contrast to setting up an aquarium which accommodates the specific needs of certain fishes or animals. 

We'll get back to that later on.

The irony is that we have given these animals “duties” in our aquariums  when, in reality, they are simply behaving as they have in the wild for eons. We’re assigning a “role” to their existence based on our needs…Weird, huh? Or kind of "arrogantly presumptive", maybe?

Okay, I can see there will be a few who will say, "Fellman, you're being sort of hypocritical in your arguments here..." Well, perhaps, but I'd love to see us look at this from a slightly different perspective... (as we're known to do now and again!)

There are a lot of animals which are selected by us hobbyists for this "role" in aquariums  Many are of debatable value in terms of consuming things that we don’t want in our tanks. Others are without debate perfectly suited for what we want them to do. Some arrive in our tanks from plants or driftwood from other aquariums as sort of "hitchhikers", in a decidedly natural manner, without our intervention.

Others are deliberately added to our aquariums as part of what we think are necessary "cleanup crews." The composition of these “cleanup crews” is a well-discussed topic…We’ve dutifully assembled rosters of animals that we feel will do the job at removing the stuff we don’t want in our tanks, like algae, uneaten food, and "detritus." (don't start me on that shit, please.)

(An "Algae Eater!" Don't get me started with this one....)

Everyone has their opinions of what animals are best, and how many you should have. “X” number of this-or-that per gallon/liter, or some such nonsense. I think it’s absurd. I mean, really, who has done studies on how much algae an individual snail will consume in nature? Yet, we as vendors and hobbyists come up with exotic formulae…based on…what, exactly? And how much algae can support “X” number of snails in an aquarium, and for how long? At some point, food supplies will be exhausted with a large population of these animals in residence.

Then what?

I mean, if I were a snail, I wouldn’t want to share my 30-gallon tank with 15 other hungry neighbors. I’d just want the space for myself, or maybe a few friends of the opposite sex. More food, more fun…If you can call a snail’s life “fun”, that is.

Now, yeah, it is a bit more of an "art" than a "science"- and no one really has the perfect answer. And sure, I sell fish stuff for a living, so who am I to make such assertions and proffer my criticisms? Well, I'm just another hobbyist asking questions. We've discussed this before, but it comes up a lot in discussions.

This is a pretty common thing in the reef aquarium world, where you see vendors selling packages of snail, crabs, shrimp, and starfishes as "cleanup crews." At first it seems innocent, but beneath the shiny veneer, it's actually kind of dark and sad: We consider these animals a sort of "disposable" and "temporary" commodity- using them for their "cleaning services" until we have no more algae or detritus or uneaten food or whatever in our tanks. Then, if they live, great. IF they perish- well, we can always get more, right?


The "commoditization" of life forms for our tank maintenance...great...

Yep, I see this in the reef aquarium world all the time:  Recommendations for large number of animals like Brittle Stars and such to handle "detritus"...One of the big problems I have with some of the more “traditional” detritivorous “cleanup crew” members is that they are often animals that consume detritus as a part of their diet, and make a greater part of their diet the micro and/or macrofauna that you are so carefully trying to cultivate for your biodiveristy and nutrient export processes.


To make matters worse, hobbyists are often advised to keep stupidly large numbers of these animals in their reef aquariums, which assures that not only will they decimate your beneficial infauna, but they’ll probably slowly starve to death as a result of their own "efficiency." I mean, Brittle stars and some of the snails we use are good at getting at detritus, but if part of what they are consuming are animals that you want in your system, particularly in your sandbed- then its a considerable tradeoff, isn’t it?

It's no different in freshwater, really. The "cast of characters" is slightly different, but that's it. The "mission" we've assigned these animals is the same: It's all about eliminating algae and "detritus" in what we consider a "natural" way.

Let’s talk about the apparent dreaded "enemy" of clean tanks…detritus!

Detritus (or “detrus”, as one of my local reefer friends annoyingly refers to it with his typical malapropisms) is a great scientific-sounding “catch all” term for “stuff” that accumulates in your rock and sand- mainly, partially decomposed or uneaten food,  mucous, fish waste, etc. The working definition is “non-living” organic material; or more properly, organic-rich particulate material. Although continuously broken down by microorganisms in a healthy, established aquarium, some of the materials are not completely consumed by these lower organisms, and can be at least initially “worked over” by detritivorous animals and fishes.

Is it bad? Well, yes and no.

I mean, if the materials in the detritus continue to break down, they can create less hygienic conditions in a closed system, or provide “fuel” for nuisance algae growth. However, if you embrace it and view it as a supplemental food source for your animals, which it is- it doesn’t seem all that bad, huh? When we've talked about deep leaf litter beds as a possible means for cultivating supplemental food for our fishes, and have experimented with "inoculating" these beds with animal like worms and such, it's not so scary!

Fungal and bacterial growths act on it, and also serve as supplemental food sources for many fishes in our aquariums...Perhaps detritus is "fuel" for kickstarting our closed ecosystems? Food!

Okay...that's it for now for detritus.

I mean, based on numerous field studies I've read, that it's a pretty safe bet that many fishes of all types will consume this stuff as part of their diet. Assigning a fish to the exclusive role of "detritus cleaner" is a bit, well...arrogant on our part. Like, they're supposed to ignore all of the good stuff you feed the other fishes and simply subsist on detritus alone?  This is, I suppose, where I admit that my argument gets a bit weaker...

But what about algae..and those snails we "employ" to take it out. We like to add snails, right? At least they're cool for a while, until they multiply. And lot of these snails will reproduce along the way, sometimes creating large populations. So what do we do? We purchase "Assassin Snails" to take 'em out.

So...We're using another animal in a limited role to solve a "problem" that we sort of created in the first place by using a different animal for a limited role...


(The "Assassin", Clea helena. Pic by Snek01, used under CC BY-SA 3.0)

So when I see people asking about fishes as designated "algae eaters", I tend to get that familiar uncomfortable feeling. Yeah, a lot of fishes love eating algae, but I think we need to look at them for what they are: Cool little fishes (Otocinculus cats come to mind) that are interesting and enjoyable in their own right, which happen to consume algae as part of their diet. Not animals that we should stock in our tanks strictly for the purpose of taking it all out.

Fortunately, many of us have sort of "grown out" of this "stereotyping" thing for some fishes...I mean, when was the last time a serious hobbyist purchased a Plecostomus strictly as an "algae eater for their community aquarium?" Or a Corydoras as a "scavenger?"  On the other hand, it's not totally uncommon to see this thinking perpetuated in the general hobby arena...


(Corydoras sp. "CW008"- The perfect "scavenger?" I should think not! )

Try running that idea by one of the many hardcore Loricariid fanciers out there, who collect, keep, and breed these amazing fishes regularly! I don't think it will go over all that well...Your time would be better spent learning how closed aquatic ecosystems work, and how algae appear in significant amounts based on a set of characteristics which arise to facilitate their growth.

So, really, relegating these fascinating fishes to "scavengers" who are in our tanks for the sole purpose of keeping our tanks clean is a little "out there", really In fact, it's unthinkable to lots of dedicated hobbyists! People set up entire fish rooms to keep these fishes in optimum environments. Entire collections are comprised of many beautiful plecos and corys.

However, I suppose it's understandable that we make up a "role" for them.  It's kind of our own fault.


We feel good about using "natural controls" for problems, and I think it's great...but we also tend to look at the fact that it's really OUR responsibility to keep the tank clean, right? We can enlist the help of animals who are known to consume algae and uneaten food...but I personally don't think we should make the only reason for any fish's inclusion in our aquarium one of a "cleanup crew" member. 

Back to snails again.. (this is like a tennis match, huh?)

If you do incorporate snails into your aquariums for this purpose-and I think you should...I say, start really small, adding just a scant few of these animals into your system at a time. Just because “experts” or vendors recommend “X” number per gallon doesn’t mean that’s an appropriate stocking level. Remember, these animals need to eat, and if they exhaust their food supply, they will perish. They'll multiply if they are happy, and if the food resources are why not start off with just a few?

Really. I mean, if the thought of introducing new algae-covered rocks and wood into your tank just to feed your large population of snails after they've exhausted the available food supply doesn’t appeal to you, then stock with just a few to start and see how they do.

Or just get really good at taking the stuff out yourself.

OR...learn to appreciate this stuff.

Yeah. Better.

You can always embrace biofilms, algae, and fungal growths for what they are: Nature's most efficient processors of biological material. Not quite as easy or sexy as buying a dozen Otos or 20 snails, but perhaps far better suited for the "role." (okay, I can see some smartassreader railing on me as a hypocrite for postulating that we "assign" nutrient export duties to fungi and bacteria...)

Let's make the effort to continue to teach new hobbyists the value of proper husbandry; the basic skills required to identify problems, concerns, and ongoing maintenance requirements in our aquariums. Understanding how attempting to re-create more natural-functioning environments and their ability to utilize nutrients and food inputs is a fascinating endeavor, and I think our botanical-style aquariums are a good place to start!

Water changes, algae scraping, feeding carefully, etc., all are more important than ever...We can't solely rely on a piece of equipment or an animal to do our jobs for us...

So sure- it's okay to incorporate these animals into your stocking plan, but be reasonable and humane in your assumptions. Treat them like the treasured living creatures that they are. 

Play an active role in the process of maintaining your tanks. Don't "outsource" all of it to the fishes.

It's our responsibility to take the initiative and to perfect these skills...It's NOT our fishes' "job"- and that's for the benefit of all!

Stay compassionate. Stay thoughtful. Stay curious. Stay empathetic. Stay diligent. Stay engaged. Stay grateful...

And Stay Wet!


Scott Fellman

Tannin Aquatics

Scott Fellman
Scott Fellman


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