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"Cleaner" Fish

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#1 RandomWiktor


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Posted 06 February 2011 - 08:39 AM

”Cleaner Fish”
Why They Don’t Exist & Your Aquarium Doesn’t Need One.
By RandomWiktor

Most novice aquarists will find themselves fighting their way through fishkeeping myths and misperceptions as they develop an understanding of their complex new hobby. While concepts like water chemistry can be broken down to an exact science, however, stocking remains one area of aquaculture that is still rife with bad information and mixed opinions. Many newcomers will rely on a pet store to recommend fish – dangerous business to rely on someone making a sale to be honest and forthright. An unfortunate result of this ignorance and misplaced trust is the persistent myth of the “cleaner fish.”

What is a “cleaner fish?”
A “cleaner fish,” in actuality, does not exist. However, when individuals refer to a “cleaner fish,” they are generally speaking of either an algae eating or bottom-feeding species that are typically marketed as fish that will improve tank cleanliness. Species commonly dubbed “cleaner fish” include the common plecostomus, the Chinese algae eater, the corydoras catfish, and a variety of other pleco, loach, and catfish species. Superficially, they do appear to be “cleaning” when you see them sucking on the glass or rooting in the gravel. Unfortunately, it isn’t quite as simple as that. Here are a few myths tied to these fish that need to be dispelled.

The Myths
Myth: Cleaner fish do not count towards your bioload.
Reality: All aquarium inhabitants count towards your bioload. A bioload is more than just a number of fish in a tank; it refers to how many fish your aquarium can reasonably sustain. An aquarium is a fish’s habitat, drinking water, air, and toilet – and yes, catfish, loaches, and algae eaters will affect and be affected by your stocking! All fish take up space and oxygen and contribute waste, so all fish count towards the bioload.

Myth: Cleaner fish do not produce waste.
Reality: Not only do the fish typically referred to as “cleaner fish” produce waste, but they often produce lots of waste. Consider a cow and a wolf. To obtain adequate nutrition from grass, the cow grazes all day on high fiber foods – and if you’ve ever been in a cattle field, you’ll know that the result is a large amount of fecal waste. Conversely, the wolf may consume a large meaty meal twice in a week, and produce a small amount of fecal waste. Herbivores and omnivores, as a general rule, produce more waste than carnivores due to the fiber content of their diet. So if you put a plecostomus in your tank to consume unsightly algae, the byproduct will be a large amount of pleco waste – and all of the associated ammonia that comes with it!

Myth: If you have a cleaner fish, you don’t need to clean your aquarium.
Reality: Never does adding to your bioload result in less cleaning, and virtually no aquarium does well without any cleaning or maintenance whatsoever. No matter how you cut it, all fish produce waste. While a good biological filter (a “cycled” aquarium) will help keep your water chemistry in check, no aquarium thrives when laden with raw waste. Sooner or later, the breakdown of these waste products will have a negative impact on your water chemistry and on your fish. Ironically, inadequate cleanliness is typically the cause of the exact problems people buy “cleaner fish” to correct; many problems can be allayed with a simple gravel vacuuming and 10-20% weekly water changes (we’ll explain more on this below).

Myth: All aquariums need cleaner fish to balance the aquarium’s ecosystem.
Reality: Remember, an aquarium is not the same as a wild ecosystem, no matter how hard we may try to create similarities. At the end of the day, our finite volumes of ten, twenty, or thirty gallons do not remotely compare to the vast ecosystems and advanced ecological processes that keep aquatic ecosystems healthy in the wild. The messy hodge-podge of half-domesticated species from different biomes (and even continents) thrown sloppily together in the average beginner’s aquarium in no way mimic the wild anyways, so the suggestion that throwing a corydoras into the mix will suddenly make it just like a pristine mountain stream is ridiculous.

The Scoop on Common “Cleaner” Fish
Now that we understand that the species known as “cleaner fish” do not, in fact, clean one’s aquarium, it is worth getting to know these fish beyond their alleged utility. What are their actual habits and care needs? Are they a good fit for your aquarium? Let’s find out.

Common Plecostomus - Often referred to as a “sucker fish” and perhaps the most commonly sold algae eater in pet stores, the common pleco is also one of the most difficult algae eaters to care for. Sold as tiny juveniles in stores, these fish can reach a length of nearly two feet - though most will die of poor husbandry before reaching this size. Being both extremely large and messy, they require aquariums in excess of 75g and a steady supply of food; underfed plecos in particular are known to rasp off the slime coats of slower, flat-bodied fish (they should not be kept with flat bodied fish as a precaution).

For the right person, the common pleco can be an impressive and beautiful fish to own if appropriate care conditions can be provided. However, for the casual aquarist wanting to maintain a small aquarium with community fish, they are grossly inappropriate.

Chinese Algae Eater - If you purchased a long-bodied brown or gold fish that the pet store referred to as an “algae eater” with no specification of species, you probably purchased a Chinese algae eater. Active, attractive fish, they are often sold as an alternative to the “lazy” (actually, nocturnal) common pleco. Unfortunately, the Chinese algae eater is also a tough fish for most to handle. While it doesn’t get as big as the common pleco - only up to 12” rather than 24” - it becomes a highly territorial and omnivorous fish at maturity. This means that the cute baby who tore through algae on the tank walls in its youth will grow up to be an adult that preys on other fish: the CAE is not a true algae eater, but rather a stream dwelling omnivorous Cypriniform that evolved a sucker mouth to cling to rocks in the fast current.

Chinese algae eaters are beautiful fish and have been kept with some success with very fast or very aggressive fish, but in general, they are best kept only by experienced aquarists who can appreciate their care needs and accept their dynamic behavior. They are certainly not appropriate for smaller aquariums due to their large adult size and activity levels, and are definitely not an ideal choice for long term algae control.

Corydoras Catfish - Cory catfish are a popular species sold in pet stores due to their small size and reputation as an excellent clean-up crew. Most species commonly available in stores will not exceed four inches in length at maturity, and their active behavior is attractive to many fish keepers. However, the cory catfish is a shoaling species: it should ideally be kept in groups of no less than six. Kept solitarily or in small groups, the fish can suffer chronic stress that eventually leads to ill health. Unfortunately, accommodating a full sized shoal typically demands aquariums of 20 gallons or greater, especially due to the activity levels of the species - a problem for someone seeking clean up in their 10g community tank. What’s more, while the cory will certainly scrounge for food on the tank’s bottom, they really need to be offered sinking wafers or pellets to ensure proper nutrition; forcing them to rely on scraps can cause them to become underweight and malnourished.

Others - a wide range of loaches, catfish, and plecos are also marketed as “cleaner fish.” While we can not cover them all here, it is very important to carefully research the care needs of each species before considering a purchase. Attention should be paid to temperament, social needs, and adult size in particular. More importantly, if you wish to buy one of these species, don’t buy it to clean your aquarium or manage your algae: these are your duties. Only purchase a fish because you truly desire it as a treasured addition to your home aquarium.

Waste, Algae, Cloudiness, and Odor: What’s Really Going On?
Most aquarists buy a “cleaner fish” for a reason: there is a problem in their aquarium. Perhaps they have algae covering the walls of their aquarium. Maybe there is a foul odor, cloudy water, or waste particles caking the surface of their gravel. These are all signs of an imbalanced aquatic environment, and they need to be dealt with by the aquarium owner - not by a fish! Here are some common causes and cures of the problems “cleaner fish” are bought to contend with.

Algae - Algae is a single celled photosynthetic colonial organism that is, incidentally, also a huge pain in the butt to fish keepers. Coating the glass, gravel, and ornaments, it is unattractive and depending on the species may become dangerous should it get out of control. Most algae growth in aquariums is perfectly preventable, however. Algae needs three things to grow: water, light, and nutrients. The vast majority of algae growth in a home aquarium is due to excessive light or excessive waste in the aquarium. By keeping aquariums away from windows, and leaving the lights on for 8-10 hours per day maximum, much of algae growth can be deterred. Reducing the amount of waste products in one’s water is also crucial; overfeeding and under-cleaning are two major causes of algae growth. Routine gravel vacuums and water changes will help, as will properly cycling one's aquarium, and adding live plants (which will compete with the algae for nutrients).

Visible Waste & Cloudiness - If your water is persistently discolored and cloudy (as opposed to a brief clouding of the water caused by new substrate or a bacterial bloom during cycling), or if you notice a layer of fish feces or “slime” over the top of your gravel, your aquarium is in big trouble - and the last thing you should doing is add more fish. Buy a master test kit and check your levels of ammonia, nitrate, and nitrite - because chances are you need a wake-up call about how often you are (or aren’t) cleaning, and how many/what size fish are in your aquarium. In a properly maintained, appropriately stocked aquarium, there should never be raw waste floating in the water or coating the substrate. These are generally signs of a tank that is dangerously overfed, overstocked, or under-cleaned - and these problems need to be corrected for the health and survival of the fish.

Foul Odor - Often coming hand in hand with other issues listed above, many aquarium owners will complain of a foul reek coming from their fish tank and/or filter. While many aquariums will have a slight “fishy” odor, any strong smells could indicate an issue with water quality. Waste building up in the filter as well as in the water itself can lead to a persistent damp stink that may be similar to the smell of a swamp or dirty bathroom. This isn’t too far off; the smell is often due to a build up of organic decay and high levels of ammonia and nitrate in the water. Use a master test kit to check your water, and adjust your feeding, stocking, and maintenance accordingly.

Conclusion: Cleaner Humans
A quote you will commonly see on aquarists’ websites reads, “We are not fish keepers, we are water keepers; take care of your water, and your water will take care of your fish.” Nothing could be a truer statement about the mindset one must have when owning an aquarium. If routine cleaning and monitoring is not your cup of tea, please do not get an aquarium; the popular misconception that fish are a low maintenance decorative pet has killed far too many ornamental fish. You must enter fish keeping with the understanding that you will be playing the role of steward to your fishes’ entire world.

While it is fine to own the species mentioned above & even make use of their algae eating and scavenging habits within a properly maintained aquarium environment, it isn't OK to buy a fish as a replacement for routine aquarium care. So… adopt the role of a cleaner human! Don’t rely on a fish to keep your aquarium healthy; your pleco doesn’t have a gravel vacuum and your cory catfish doesn’t have a master test kit. Read up before setting up your fish tank. Cycle it properly before adding fish to minimize harmful levels of waste chemicals from building up. Gravel vacuum and perform partial water changes weekly to ensure that your fish have a clean and safe environment. Monitor closely, filter well, stock lightly, and care generously. You WILL have a clean and healthy aquarium.

Rules for Distribution
This article is free for distribution and use under the following conditions:
1. Do not modify the content of this article
2. Do not claim part or all of this article as your own.
3. Provide a credit to RandomWiktor and a link (if applicable) to UltimateBettas.com

  • Saucy, Gilraen Took, VelvetDragon and 13 others like this

#2 Solitarianknight


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Posted 06 February 2011 - 09:29 AM

You are both a scholar and a genius. Bravo my friend.

#3 cichlidfinder


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Posted 06 February 2011 - 05:33 PM

Ha I knew you would get it done.

Good job ! :thumbup:

#4 Gtdad2


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Posted 07 February 2011 - 01:28 AM

Nicely done :notworthy:

#5 Laura Lee

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Posted 07 February 2011 - 09:59 AM

Great write-up, Ren!

I'll just toss in- a few options that MAY be appropriate clean-up crews for small tanks include:

Dwarf shrimp (Amanos, Red Cherry, Tiger, etc). Most species currently in the hobby will eat algae as well as scavenge leftover food. However, shrimp are part of the natural diet for most species of fish (including bettas), so select tankmates with care. Filtering shrimp (Bamboo shrimp, etc) are NOT suitable cleaners for small tanks due to specialized dietary needs.

Snails. There are many, many different freshwater snail species available to hobbyists these days, and most are scavengers that can work as a part of a tank's cleanup crew. Some of the most common are Mystery snails (several different species of snail get sold as Mystery snails, most are Apple snails), Ramshorn snails, Pond snails, Nerite snails, Malaysian Trumpet snails, Rabbit snails, and Assassin snails. As always, do your homework before purchasing any of these, as they have very different dietary requirements. Some are algae eaters, some carnivorous, some will eat live plants, etc. Some species are very, very prolific breeders and can overrun a tank quickly.

Otocinclus catfish. A very small, gentle catfish (most stay around 1-1.5") that will eat many different forms of algae. These catfish are extremely sensitive to poor water conditions and need a regular supply of fresh veggies to keep in good health. They have a reputation for being very delicate, especially as most in the hobby are wild-caught and imported from South America. The trip is usually very hard on them, and it can be difficult to find fish that are in good health at the time of purchase. They do best in well established tanks that are heavily planted with live plants. Like most catfish, they are schoolers and should be kept with others of their own species. 3 is a bare minimum. Otocinclus.com is a very good resource for further research.

Dwarf Cories. There are 3 species of dwarf Corydoras catfish most commonly available in the hobby- C. pygmaeus (the smallest, approximately 1 cm in size), C. hastatus, and C. hasbrosus (just slightly larger than C. pygmaeus, up to 2 cm). Like all other Cories, they are gentle, schooling species and need to be kept with companions of the same species. A school of 5-7 of these would fit easily into a well maintained 10 gallon tank along with a (friendly) Betta. C. pygmaeus and C. hastatus will spend much more time swimming up in the water column, while C. hasbrosus will spend most of their time down on the bottom of the tank like other Cory species. Be sure to "target feed" them appropriate foods (there are many sinking catfish wafers on the market that are easy to use) and do not rely on them to thrive just on "leftovers" from other fish.

As Ren so eloqently stated above, all of these WILL add to the bioload of a tank, and are NOT a substitute for regular tank maintenance by the responsible hobbyist!
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#6 Strick


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Posted 07 February 2011 - 01:33 PM

This is wonderful, Ren! Very, very good work. One suggestion:

Myth: Cleaner fish eat other fish's waste.
Reality: No, they don't. I don't care what the guy in the store told you, no fish (or shrimp, or snail) will eat poop. Until someone develops an aquatic version of the dung beetle, only the nitrogen cycle and/or a gravel vacuum will get rid of it for you.

I still hear this all the time in PetSmartCo and Wally World...
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#7 RandomWiktor


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Posted 07 February 2011 - 04:25 PM

Thanks for the add-ons, Laura Lee and Strick; I hoped to see some of your feedback on here since you are both our resident "healthy, happy tank" experts :thumbup:

#8 Mushu_Jade



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Posted 19 November 2012 - 07:59 AM

My fiancé had some bronze cories that tried to scavenge live fish, they ended up killing 3 of his guppies, because he didn't target feed. So sometimes even the sweet and gentle Cory will attack other fish if they're hungry enough!

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