Hi Kristie, and welcome to Tropical Fish Keeping forum.
I would get rid of the Serpae Tetra. If this fish decides to follow its natural instincts as it matures, it will cause you trouble. It must be kept in groups of 8 or more to contain aggression within the group, and in a 35g it should be the only species. A 55g (4-foot) tank is the minimum recommended size for a group of this fish if other species are to be included. Have a look of our profile on this fish; click on the shaded name in posts or use the second tab from the left in the blue bar at the top to access the profile section.
As 1077 pointed out, these fish are all shoaling which means they need to be in groups to be healthy (less stress), at least 6 [aside from the unique Serpae as mentioned above]. Diamond tetra get largish, and a group of 6 would leave no room for Congo Tetra which attain 3+ inches and need swimming space as do the barbs, at least a 4-foot for Congo. They are too beautiful a fish to be given anything less.
No mention is made of water parameters, some of the common tetra are relatively adaptable being commercially-raised fish, some however are not and soft slightly acidic water is required. We have most of the available tetra listed in the characins section of the profiles, and most of the commonly-seen danio, rasbora and barbs under cyprinids. Info on water requirements, compatibility, tank size minimums, etc. are included in each species' profile. Any questions, fire away.