The grey spotty one is a Leporacanthicus joselimai and the smaller brown one is a female (I think) Bristlenose.
Wet wet wet, do you own a golden nugget (the pic next to your name)? I bought one a few weeks ago. I find it to be nocturnal at the moment and it doesn't seem to eat a lot but it does look cool.
I went to the website planet catfish to try to sex the grey one and it said that Adult males have a much longer and broader head with small odontodes on the side of the head, more odontodes on the pectoral fin spine and on the whole body, a bigger dorsal fin and normally a prettier colouration.
Well Ive no idea whether its male or female?!
Billy