does it look like the on in the pics below? from best i can tell it looks like a regular brown bristlenose pleco. but ur pic is too fuzzy to say for sure. let me know if hey look like these.
It looks like: "Scientific Name : Hypostomus plecostomus
Common Names :Suckerfish, Suckermouth Catfish Care Level : Easy to moderate Size : Up to 18 inches (46 cm) pH : 6.5 - 7.5 Temperature : 73°F - 82°F (23°C - 28°C) Water Hardness : 5° to 19° dH, Lifespan : 10 - 15 years Origin / Habitat : South America Temperament / Behavior : Generally peaceful, but can be aggressive toward others of the same species. Breeding / Mating / Reproduction : It can be very difficult to breed them in a home aquarium. Tank Size : Depends on the type, but a 55 gallon minimum for the common pleco given its large adult size. Compatible Tank Mates : Many, given the mostly peaceful nature of this fish. Diet / Fish Food : Herbivore, try to supplement their diet with algae wafers Tank Region : Bottom and the sides of the glass. Gender : There are no visible differences between the male and female."
Woofy, I don't think that mine is a bristlenose. it's shorter and wider than in the photos above
As for the markings, the Hypostomus doesn't quite look right either. Mine has a mostly black body with similar stripes to the Hypostomus on the fins and tail.
if it was something other than a common pleco, i am almost 100% sure you would know about it. a pleco other than a common pleco or 'algae eater' or 'suckerfish' usually commands a higher price. in order to get customers to pay the higher price the stores have to let them know what they are buying. in my experience, small commons usually run $2-4, while young bristlenoses will be twice that, and all "exotic" plecos i've seen have been labeled somehow in order to justify their price, whether or not proper scientific names are used. getting a fish from an individual who was selling their fish and couldn't remember what they had is a different story and you may indeed wind up with something really cool for cheap, but just getting a random pleco from an LFS for a few bucks means you got a common. depending on exactly which species you have (there are at least three that fall under the 'common' name) your fish can range anywhere from 8-24 inches fully grown.
Secondly,
Without better pictures this is extremely difficult to identify.
It could be the pardalis, or it also kinda looks like Pterygoplichthys scrophus. Just based on the striping down the back. But without better pictures, we may never know until you either end up with a 12" catfish or a 24" catfish.
Lastly, your lfs has lied to you. Goldfish are not good for cycling a tank. Heres a link that discuses a fishless cycle. Also you could ask your lfs for some filter media that you could place in your tank while you cycle it. This process is much safer.