...but it also says 55 gallons plus and their maximum size is 24 inches.
Product Description: Item: 3954163
* Diet: Algae Wafers, Fresh Vegetables
* Maximum size: 24"
* Water temperature: 72-82° F
* Swimming level: Bottom
* Experience level: Beginner
* Tank Setup: 55+ gallons
Still, 55 gallons is most likely going to be too small for an adult common pleco anyways, even by itself.
And even though it says 'beginner' it then goes on in the description to say "Algae eaters should not be kept by beginners or in a community aquarium with delicate fish. As adults, they can be aggressive to other tankmates and should be housed with large, tough fish or as a single species in the aquarium."
I would think beginners who would be turning to 'petsmart' for their information rarely, if ever, get plecos to house by themselves anways. How many beginners go into the store thinking, 'hey, I want a nocturnal fish who hides under a rock out of view all day, produces disgustingly visible copious amounts of waste, is a mottled dark brown/black color, and grows to massive size.' Not many, probably (perhaps Noddy did, but he thinks everyone should "plecostomus, like the rest of us"). And how many beginners are going to, indeed should be housing them with large, tough fish?
The biggest mistake is by beginners who buy them to basically be a 'cleanup fish' without realizing:
A. They have negligible, if any, real cleanup effect, and regardless need supplementation to their diet. Sadly, many plecos starve b/c their owners think they only need the nutrients that the tank produces. This can also lead to sucking on the slime coats of other fish, leading to owners to come to the mistaken conclusion that they are aggressive rather than a simple response to insufficient food availability. This is endemic of the idea that a pleco is a 'trash fish' that is only there as a auxiliary for the other, more valuable, 'display' fish. There are a ton of 'Pleco fanatics' in Battlestar Galactica and Star Trek T-shirts who would wholeheartedly disagree. too.
B. They produce far, far more waste than they clean. Far, far, far, far, far, more waste.
C. The most common species sold in pet stores grow to massive size. This is precipitated by nutrition and water quality primarily, so 'growing to the size of the tank' is a misconception, for the most part.
