Either Gibbiceps or Common Plec (No expert really, they llok the same to me, although I have 2 commons). They will grow anywhere between 12 and 20 inches. dependant on each fish and the conditions etc. so they are a definate TANKBUSTER. they grow quickly as well. be warned and good luck
Looks like a common plec, we have one, it is around 8 inches now and will grow to around 12 inches, a 60 litre won't be big enough for it, we have it currently in a 125 litre and I'll be moving it on soon cause it just doesn't have the swimming room without knocking plants out of the way.
If he's a common or a gibby (cant tell by the pic sorry, got any more?) he'll need at least a 4 x 18" x 18", preferably by 2ft. I'd personally go no smaller than a 5ft x 2ft x 2ft for one, but that's personal choice. These fish not only get big, but they poo for England, so you'd need a big tank with excellent filtration. Commons can get to 18", gibbies can get to 2ft.
Unless you're looking at a tank upgrade in the future, I'd probably return him as I dont think there's many plecs that would be suitable for a 60l (I'd normally recommend a bristlenose for a good smaller plec - but even those get to 5-6"). Queen Arabesques stay quite small, but to be honest would still probably need a bigger tank. Otocinclus might be a better idea?
wolf - I think 250G is a little excessive. I'd say at least 100g, but certainly not 250g - I've got two commons, a rusty, a bristlnose and an L203 in a 180g!
These ones are really bad cuz that when my tank was really neglected - since then I have rekindled my hobby seriously - since then my tank is much cleaner
He's a Liposarcus (probably Liposarcus pardalis) aka "common plec". He'll grow to 15" standard length (standard length doesn't include the tail) according to Planet Catfish. Lisa's tank size recommendations are spot on
He looks exactly like one of my common pleco's. There are two main species of fish which are regularly put under the title of common pleco, one which grows to about 8-10inches and one that grows to 14-15inches+. Unfortunately its that larger type that is the most commonly sold, so if i were you i would plan for the largest tank you can get that will accomodate the pleco nicely when its fully grown.