My Corys'

[Jcartwright]

I have 3 little corys' in my tank and i'm concerned about 1 of them. I've had them for about 3 months now and 2 of them seem quiet pally with each other where as the other swims around on it's own. Just recently i've noticed that this one has a bid part of it's dorsel fin missing and it's tail fin. It seems quite happy swimming around and the other fish in my tank are ok(see below for my tank contents).
The other 2 aren't attacking it, are they? they don't seem to be.
should i get another cory? I was thinking of getting another 3 corys' so then i have 3 pairs.
Should i be concerned? What could it be?

 

[CaraC]

As i have heard cories need a minimum of 6 to thrive and be happy, however i have 6 cories 4 are the same 2 are albinos and i always find that 1 albino and 1 emerald go off to themselves unless food is involved. As far as the fins, sometimes they can become caught in nets and other fish may be nipping at them when we arent watching, however i do not know how to treat that if its fin rot. If its from fighting then clean water for several weeks (lotsa water changes) should help immensly for the fish to heal on it own.
I just noticed u have dwarf gouramis. Are they in the tank with the catfish?
They may be your cluprits in tail nipping, especially during feeding. I would watch the gouramis when they think you are gone for about 20 minutes.