i think glass catfish are meant to be kept in groups, and can be quite demanding in terms of water quality...are they definitely going to stay?
...i used to have a 90 litre with a pair of kribs, a BN plec, and then a decent shoal of black neon tetra. had some big bits of bogwood and loads of plants (fake) and was the set up that ive been happiest with since i started the hobby.