"I need a pleco to keep my tank clean"

[Brhino]

Lately I've been seeing a few threads in which people have purchased or are looking to purchase a pleco because they think it will "clean the tank". Some people have even been under the impression that plecos and other bottom feeders eat fish poop. I wanted to set the record straight with some photographs.


This is my pleco. He's a sailfin pleco - similar to the common plecos that you most often find in stores. Like them, he was available for purchase at a small size - about 3" - but he'll soon be getting much, much bigger. If you notice the white specks on him don't worry - it's not ich, it's the white sand that I have mixed in with the black in this tank.

This tank is not for display, so I haven't bothered removing any algae growth. This little pleco has done a great job of that. He cleans the glass and the decorations, and there is no longer any visible algae anywhere. He will become less interested in algae as he gets older for what it's worth.

So, on one hand, you can say that this pleco is cleaning my tank. But on the other hand, consider this:

This is what all that algae (plus zucchini and regular fish food) has been turned into: pleco poop. This tank's substrate was completely cleaned three days before this picture was taken. There are other fish in the tank but everything you see here is from the pleco - and that's just one end of the tank!


In fact, he was busy making more poop while I was taking pictures!

Now, none of this is a complaint. I have two plecos and they're two of my favorite fish. I wish I had more of them. But I didn't buy them expecting them to be something that they're not. They do take care of algae to some degree but in return they give you massive amounts of poop. As always, the responsibility of keeping the fish tank clean and maintained belongs to the fish keeper, not the fish.

Now, if you'll excuse me, I'm off to find my gravel vacuum...

[Aeonflame]

Good point. Plecos are poop machines. And while algae is unsightly, its better for an unplanted tank than poop.

[steeler1]

Glad you posted these pictures, now we have proof to show people how much waste the can produce.

[~firefly~]

Very good post!

I bought 10 otos to take care of a brown algae outbreak in my tank, and JEEZ did they poop! Every day, literally, piles of it to hoover out...such was the scale of my brown algae issue. They effectively took all the algae off everything, recycled it inside their bodies, and pooped it out on the substrate (which was easier for me to clean up than the algae).

They certainly don't reduce/consume waste, they just repackage it.

[Orion5]

I'm glad you made clear that plecos don't eat poop and "clean the aquarium." I am sure I'm not alone in overhearing pet shop employees tell people this is exactly what they do. On a couple of occasions I confronted the same customers outside the store and told them the truth.

[Shidohari]

god even if i wanted an algae eater for my ten gallon tank, which i don't, this is totally turned me off plecos, at least for tanks smaller than 20 gallons or unplanted tanks.

[chocological]

Plecos seem to be good for planted tanks. Poop being fertilizer and all.

[Zander]

There seems to be a misconception among newer fish owners that "every tank needs an algae eater".

Plecos do a solid job keeping the walls clean but they do a mediocre job on decorations, lousy job on plants (eating/nibbling them on occasion), and they actually make the gravel much dirtier. I like the photograph you posted it really drives that last point home.

I don't care how bad your algae is, you don't "need" one. At least not for the algae. There are about a dozen things you can do to decrease your algae, and you could even get every type of algae eater in addition to that and you would still need to clean your tank sometimes. You should buy the fish because you like it, eating some algae should be a benefit.

Beyond that, people should not keep algae eaters in 10 gallon tanks. Only Otocinclus cats are small enough for them and they should be kept in schools. You could probably keep some in a 10 gallon but you wouldn't be able to get very many and that would be an issue. Having only one or two isn't ideal.

[~firefly~]

I found it impossible to keep plecos and plants successfully together. They grow so big and strong that they would just tear through everything and uproot the lot (mine were 10 inches and 12 inches when we had our 6 foot tank). They did keep the glass clean...but that's about it!

[Goes to 11!]

Excellent thread Brhino [I rated it a 5 :-D].

Yep, Plecs are poop machines, 'Nuff said.

Firefly there are plenty of smaller plecos that coexist with plants just fine, Just not the ones you had :-P.