From what I understand, these fish will eat little animals that live in the "aufwuchs" (biofilm) on rocks and such. They may not "know" that dry food is actually food, so using small live-food would probably be your best bet.
OK, first of all, make sure you've got Chiloglanis, their care is very different from other African suckermouths. Secondly, temperature shouldn't be higher than 76F and you should have at least a strong airstone but preferably power filtration. Water quality isn't otherwise that important, neutral pH and a reasonable water change regime. Finally, the thing that surprised me about these fishes is they are really territorial, three fishes in a 24x15x15 tank is two fishes too many after they settle!
Feed frozen or live bloodworm until you see the fishes eat (which they will do normally during the day). If they don't eat, I'd suggest you've got unsuitable conditions or "too far gone" fishes. Otherwise, after a while, they will take pretty much any dry foods like flake etc. They are really rewarding being active and visible all day.
I've got also Euchilichthys guentheri in the same tank and they are doing fine. They started eating in a few days and i expected the same from this little fellows... But the Chiloglanis do nothing, just hanging on there spot. They aren't territorial at all (for now) as they are sitting so close to each other.
I don't have a very high flow but they don't seem to care as they aren't sitting in the flow...
Living food doesn't change a thing (just tried).
Could they be impressed by big fish in the tank or should it be the Oxygen who are to low? But why don't the Euchilichthys care?
I think i will try to get some extra flow in there corner, to see how they react to that...
Do you have sand in your tank? I had the same problem keeping them in a tank with the sand and low current. They were very aggressive to each other and ate nothing, they looked disgusted by the sand . Then, I transfered the Chilos to a tank with gravel and a very strong current (25-30x of tank volume), no problem since then. They are eating almost everything (live bloodworms, spirulina and normal Vitakraft tabs getting them very wild!) and they are very peaceful. No problems for 5 months now.