hi
agressiv? no. just a little rougher than borneo-types. pseudogastromyzon differ in the way to go into the concurrent: quick as a flash and return to a save place. that's a foreign "language" for gastromyzons, which are "dancers"! but as soon the place is kept by the assaulted, the repertoir is common: rumbling, pushing ...
http://www.youtube.com/watch?v=uGZjNteBqCc
just one thing: against bigger specimen as s. wui, adult b. kweichowensis, sewellias they have not the slightest chance with a flash-attack and change to the common fighting rules
if you mean towards other species - not bodysucker-types: no.
but they wipe away all from "their" favourite stones: shrimps, snails (if they could!), even little lineolatas of 10 mm as concurrents, something sewellias don't (may be the
juvenile patterns are made just for this; an interesting issue for a scientific work!)
that makes: in tank with pseudogastromyzon and other bodysuckers you will have a lot of interesting going-on. this species is an exellent sand-dweller as I've never seen before, reminds me of my lamprologus speciosus going headfirst into the sandhills.
cheers charles