Should the role of "scavenger" in the aquarium be an endangered species?

I've brought up this topic before, but I can't help but wonder...

Hobbyists who create "community tanks" are always advised by "the books" or "experts", or whomever to include some "scavengers" in their fish mix to help "consume uneaten food and algae." Now, on the surface, this seems just fine and appropriate and sound, but when you think about who fishes feed in nature, with most being largely "opportunistic" or "constant grazers", it's not too much of a stretch to think, "Well, doesn't every fish sort of 'scavenge' at some point during it's day?"

Why do we need "dedicated" scavengers?

Oh, sure, if you have a tank which only contains Marble Hatchetfishes, which exclusively feed from the surface and have those upturned mouths to back it up- okay, someone has to pick up the pieces (literally) which fall to the bottom, otherwise you'll be in there daily siphoning out uneaten food. That beings said, how many hobbyists have a 100% exclusively Hatchetfish tank, lol?

Maybe a better example would be a dedicated breeding tank, where you keep some small Corys our whatever, to consume "uneaten food" that your baby guppies or Platys, etc. would miss. I suppose I can see the benefit...but you're doing water changes anyways, so you can siphon any of these "uneaten food" away just as easily when you're in there daily, right? Maybe?

Well, getting back to this concept that the role of "scavenger" is kind of an artificial construct of aquarium keeping...Sure, some fishes are better "equipped" for the role of finding uneaten food or algae, but really, most fish could do at least some of the job. Sure, the little Otocinculus are little algae eating machines, and consume just this and really nothing the point where if you have too many of them in a tank without sufficient algal growth, they're going to start dropping like flies. And yet, in nature, they're found in larger groups, and we know they tend to do better in this social structure in the aquarium as well...yet the paradox exists that if you have 25 of them, they're likely to tear up all the avialble food in weeks and simply starve...

What to do?  Well, you could have smaller groups, of course.

And  you could stock your aquarium with other fishes that are not "rat-holed" into the role of "scavenger" or "algae eater"...fishes which are omnivorous or herbivores, and display "grazing behaviors"- you know, like some Mbuna and certain characins, etc. Now sure, I'm not suggesting to stock your aquarium with "Zebras" and "Labs" or whatever to use as "algae eaters"- that's ridiculous. What I am suggesting is that you can sort of "exploit" the fact that many fishes will feed on multiple food resources in the wild, depending upon what's available seasonally.

And, as we've all seen, fish will eat just about anything in the absence of other foods... The horror-like scenarios of Tetras or Danios that we've all seen, picking at the dead body of a fallen tank mate in the LFS, although incredibly disturbing for most of us, are just an example of this kind of adaptation...In nature, nothing seems to go to waste. Now, sure- there are fishes which perhaps "specialize" in consuming dead fishes or whatever, but they'll eat other stuff, too.

I've seen many cases where a tank full of characins like Pencilfishes, for example, begin picking at algal growth on rocks and wood throughout the day as part of their "routine." And If you find yourself out of town for a period of time, unable to feed them daily, you'll often return to fishes which seem just as fat as when you left them. What are they doing? They're consuming the foods that are available to them. They're taking advantage of what is in their environment. Although not significant consumers of algae and biofilms and such, many fishes will consume these items when their preferred foods are not available.

Even the dreaded "detritus" is food for many, many fishes.


Do we really need to add fishes into our community setups for the exclusive role of "scavenger" or "algae eater", or could we simply stock our aquariums with the fishes we love and understand that they will be resourceful, consuming what is available as it's available...Like they've done in nature for eons? And can't we just feed carefully and remove the excess, if any accumulates?

I think we could.

Just a quick thought. 


Stay engaged. Stay excited. Stay curious. Stay resourceful...

And Stay Wet.


Scott Fellman

Tannin Aquatics 



Scott Fellman
Scott Fellman


1 Response


October 10, 2017

I think something that often gets overlooked when it comes to “scavengers” is population size. So many people will keep one or two corydoras or kuhli loaches, because they don’t really have that much waste to clean up… ignoring the fact that these are social creatures that do better in large groups. I think that a lot of people miss out on the best behaviors of these fish because of this!

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