The starlight variety would not be the safest course. those are on the larger side of the bristlenose group and get to 8".
It can be quite tricky telling young commons from young bristlenoses but check out planet catfish:
http
/www.planetcatfish.com/catelog/loric...cistru/48_F.PHP - this is listed under 'bristlenose'
http/www.planetcatfish.com/catelog/loric...cistru/49_F.PHP - this is the 'common' bristlenose
there are several other fish often sold under the name 'bristlenose'. The one I have seen most often is ancistrus temminckii (different site):
http/www.africancichlids.net/Catfish/A_temminckii/
http/www.planetcatfish.com/catelog/loric...ostom/580_F.PHP - common pleco (the 'true' one) This is no longer the only 'common plec' available at LFSs. h. punctatus being another one.
Most 'ancistrus' species are considered bristlenoses:
http/www.planetcatfish.com/catelog/loricari/G_4.PHP
As you can see, it would be rather difficult to pin point a single bristlenose or common plec species so comparing the two is pretty much impossible. What I would suggest is either looking for a more mature bristlenose so you can see its bristles or taking some pictures of the fish at your LFS and then comparing them to identified pics on the net or posting them in the catfish forum for identification. I am not a plec (or catfish) expert and wouldn't realy be of much use there but there are others on here who are amazing with plec id.
I know that probably causes more confusion than it explains stuff but you can at least see why I hate common names
edit: wanted to add that you can keep the bristlenoses singly. If you know how to sex them, a pair is fine, but they are otherwise territorial and preffer to be alone.
ok, another edit: Animation, large plecs do grow relatively slowly so I see why you'd think keeping them in a small tank is ok while their young but moving fish from tank to tank is stressful for them - can even kill them and you have to also consider that a lot of people neglect to upgrade or return the fish when it's large, putting it off endlessly. Others become attached and decide to follow their own desires, ignoring the wellfare of the fish. For those who keep them to a relatively large size and do return them, most of the returned fish don't get sold because of their size as, even people who do have room to house them, tend to go for smaller fish so as to match up with the size of their other young fish (eg: if I'm starting up a realy big tank with lots of large-growing fish, the fish I get will be juveniles mostly so I won't want a gigantic plec to go with them). You also need to consider that, though it may not be obvious, large fish are negatively affected by being kept in smaller tanks and their growth rate slows, they become stressed and, therefore, are more susceptible to disease. Lastly, consider the people who DON'T have large enough tanks, don't know the potential size of the plecs and don't have plans to upgrade/return the plec. If people who do know about their potential size go and buy baby plecs, planning to return them later on, we fuel the industry, encouraging the LFS to order more, and more, and more. Lots of large, unwanted plecs are returned and, perhaps a few find homes, but there are already enough people going into LFSs and being confronted with a huge batch of baby commons because people keep buying them whether they know they can't keep them or not. A lot of the adult fish will end up crammed in some LFS or in a small tank soemwhere. They'll eventualy die prematurely.
BTW, I appreciate how messed up my typing is today - my thoughts are hyper and confused
The general point I was trying to make is that we should only buy common plecs if we have the tank for them.
