Help! Glass Catfish

i have recently (earlier today) bought a new glass cat for my other two to try and start up a shoal. All has been well. However, i just found my new glass cat with a tear, piece, chunk kind of missing from his bottom fin. I'm sorry i dont know what the fin is called. i would assume it's more of an injury than a disease and may have had it before i had bought him. I just want to lay any of my concerns and worries to rest with some knowledge.

did he maybe injure himself in my tank?
did one of my fish do something to him?
will it grow back?
should i exchange him for another glass cat at my LFS?
overall, will he be okay?

55 gal.

water params (just in case):

ammonia:0
nitrites:0
nitrates:.3
ph:7.4
temp: 77

tank mates:

red tail shark (juvenile), 1 1/2 in.
gold dojo loach, about 5 in.
2 male swordtails, 2 1/2 in. and 1 1/2 in.
male betta, 2 in.
2 other glass cats, about 2, 2 1/2 in. each



here is the missing peice of his fin:



.. and yes i know he is painted (boo, hiss, baa, whatever)

hmm, it's pretty uncool of you to stimulate demand for dye injected fish you know?

doris

probalily another fish



why on earth do u want a painted Glass Catfish

There cool enough as it is