Another thing I'd like to bring up...
Take some photos when you've got the opportunity of your pleco. Get a top photo, side photo, mouth+belly photo.
I say this for identification purposes, because there are many black and white spotted plecos and often get misidentified or mislabeled in stores. Many get a decent size, so it'll be reassuring to you if you know for sure 100% what you've got.
Example, this guy was sold to me as a snowball pleco (L201), which upon receiving, he was definitely not. Expected to get a pleco that stays 4-6 inch range and instead I got a L240 vampire galaxy pleco which gets 9-10 inches!
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Unsure if you know or not since you were expecting a different fish, but plecos do need some good oxygen levels. So either a good air stone or a powerhead is very beneficial. Pay attention especially in warmer months because warmer water has less oxygen in it, and plecos don't fare well with less oxygen.
It's very normal for plecos to hide, many of the non-mainstream pleco species are notorious hiders and that's part of their charm in a way. They're usually very nocturnal. So feeding the pleco at night is often a good idea to ensure they're provided for. Most species are vegetarian, but a few are actually carnivores (such as my L240). Wafers, large sinking pellets, and slices of things like zucchini or cucumber are often good. Carnivores enjoy a bit of chopped shrimp too.
You can often scape the tank with a way that allows better views of the pleco, such as placing caves in areas where you have a clear view of it, but still in a sheltered area for pleco security. Having one cave in a higher flow area and one in a slower area is a good idea as well