Depends entirely on the species. 'Bristlenose Plec' as a description pretty much only manages to describe a common feature in the genus. It's a loose name given to a variety of closely related species sharing common features which are hard to distinguish.
The word Plec or Pleco, short for Plecostomus is another example of a common name used to identify similiar fish. Whereas in fact most species identified as such are not in fact Hypostomus plecostomus from which this name originates.
Most commonly available 'Bristlenose Plecs' you'll find in your lfs will average 10-15cm though knowing the specific species is the only way to be sure.
Those of the genus Panaque are specialised wood eaters, bristlenoses are genus Ancistrus, bogwood doesn't constitute a major part of their diet. Given adequate roughage elsewhere in the diet they can live quite happily without it.
They will rasp on bogwood on occasions though many will do so purely to feed on the algae and aufwuchs growing upon it.
Although not strictly critical to the well-being of Bristlenose plecs I would always advise addition of at least some bogwood. The wood simulates the aquatic environment they would likely live in in the wild and increases surface area for grazing which is important to bulk-grazing species like Bristlenoses. In addition, as and when they do rasp on the wood it certainly won't do them any harm and adds to variety!
So in summary, not strictly essential so as long as diet variety is good and food selection is suited to his/her dietary needs you could certainly remove it. Be mindful though that features like this can often be a great comfort to some species.
I can only advise against buying a fish which will outgrow the tank it lives in someday. It's next to impossible to judge when a fish has outgrown it's tank because the very nature of living in a tank too small is that the fish will often stay un-naturally small for its age.
It would be worth getting a guarantee from your lfs now that they will take this fish from you some day, adult Dragon Wrasse are very different in appearance to juveniles, a lot less sought after, they are also huge, many shops won't want to take a beast from you which has little re-sale appeal.
As a general note of advice to readers, always buy a fish you know you can support it's whole life, who wants to have to give up a beloved pet some day because they can't afford/don't have space for the environment it needs to thrive/survive?
Golnugget wrote: though I agree completely this should be done in a reasoned and rational manner wherever possible.
You're construing activism with argumentative or militant behaviour. Activism shouldn't be pre-conceived as a negative behaviour.
We each have our own ways of encouraging change in perceptions. Because I don't go out and buy a poster printer and boycott a local fish shop does not mean I am neither bothered about animal welfare or am not actively seeking it's improvement.
I'm very surprised you could read anger where there was none in my earlier post. I'm not angry about the hobby in the slightest. I just have frustrations.
I don't think going away and not voicing them will do anything...
I've always respected your moderation and un-biased approach FF. I hold yourself, Suey, Cathie and Admin in the highest regard as moderators, and as mentioned I understand you have a very tough job.
I refer to a couple of individual events in the past which caused me to be particularly frustrated at the outcome, hence why I can understand where people's frustrations arise on this issue.
My post above was in no way personal, I'm past arguing about individual actions where as I may have done before. I just don't think we should rest on our laurels and ever stop striving to improve the advice we offer.
To me the first looks like a Diamon Watchman (Valenciennea puellaris) Can you get a clearer picture or describe the colour and patternation in greater detail? I'd rule out the blue cheek goby (Valenciennea strigata), I don't think it's that.
The second one looks like an Orchid Dottyback (Pseudochromis fridmani)
Noticed the Dragon Wrasse (Novaculichthys taeniourus) on the second pic, this guy in a big tank???!