From what I read when researching Ctenopoma acutirostre, buying just two is quite a risk, it has to be one or a group of 3+ (just like Panda Garras, albeit these guys can do nothing like the damage a Ctenopoma can inflict).
I bought a group of five babies (~2.5cm TL) initially mid summer, but one mysteriously vanished without a trace within a few weeks in the Rio240 and then I lost another in early September in the 150g during a horrid ten day period of fishkeeping (I lost two of my Humphead Glassfish, in hindsight almost certainly down to my stupidity of installing a Hydor Magnum 8 powerhead, which recently went into "Seffieuk"'s marine setup). By December, the remaining trio had grown to ~6.5cm TL, when I took what I thought was a big gamble by introducing a ~11cm male Ctenopoma into my 5-footer (he was looking so unhappy in the bare fish store tank and was a steal for £10). Luckily for me, the young trio accepted their "new leader" and they give him plenty of respect, but the equal-sized trio regularly chase each other.
I guess this was the point of my novel, in that they form a hierachy and in a duo the submissive one will probably be constantly bullied and in a 30g, it will have very little room to hide.
I really like the idea of a nice group of P. buffei, with those lovely striped bodies; midwater tight schooling; peaceful nature (much like the smaller Shadow Catfish that I fell in love with recently at Aquajardin, after IDing them at home, but now I'm concerned about how these blackwater fish will do in my gH 14 pH 8.2 tap water). Its worth mentioning that P. buffei loves current, which creates a conflict with ABF. They are oddball in that they are very social midwater swimmers
Just recently I was considering the idea of turning my Aqua One 620T into a catfish tank, with small species that occupy different regions of the tank...
- K. minor; P. buffei or Hyalobagrus flavus group midwater
- Oxyropsis acutirostra (Tiger Oto, on Kesgrave Tropical Ebay store) group, to add to my Hypoptopoma sp.2
- A group of Synodontis nigriventris
- My current mystery Tanganyikan catfish (Phyllonemus or Laphiobagrus) with some conspecifics if its one of the social species in this group, if not add a group of Sterbai Cories
But I'm concerned P. buffei will be too active for my setup (sounds much better for your 36" long tank) and I'm wary of adding Shadow Catfish with my pair of ABF up top (right now I don't think I can move them to another tank), even if the H. flavus were fine with Southampton water.
Anyway, I'm waffling now...