If you're talking about a betta then that's pretty common. They really only go after stuff with really large flashy fins.
Pleco sounds like you're setting yourself up for trouble because most of the ones you buy at pet stores are super messy and grow to be like a foot long (or more). When I worked at a fish store I recommended people not buy them. xD Best bet is getting a little group of like five otocinclus and then keeping your tank well maintained and al;ghawketyaksdghaswe now you all have got me talking about fish