Sorry to disagree with others, but neither species is suited in this situation.
The Congo Tetra,
Phenacogrammus interruptus, needs more space, at least a 3-foot (90 cm) tank, preferably 4 feet (120 cm) length. It needs a group of at least six, but will be better with a few more. It is not as active as most barbs continuously, but it does have bouts of active swimming and likes to run relays down the tank. As males can attain close to 4 inches (9-10 cm) it needs space for this.
http://www.seriouslyfish.com/species/phenacogrammus-interruptus/
The Colombian Tetra,
Hyphessobrycon columbianus, also needs some space, at least 3-feet (90 cm) tank length, as it likes to swim now and then too. However, when combined with sedate fish like angelfish, this species frequently nips fins; not as bad as some tetras, but still a risk. A group of 8 or more is said to somewhat reduce the risk, but I would not combine these.
http://www.seriouslyfish.com/species/hyphessobrycon-columbianus/
A 30g is not large space for the angelfish itself as it matures, but you can find some suitable tankmates. The more sedate tetras, like the Rosy, Roberti, Red Phantom, do quite well. Corydoras are fine for the lower level.
Byron.