These are barbs, I assume the "tetra" was just a slip.
Pethia padamya is a lively but peaceful fish that will normally do well in a larger aquarium with similar-sized non-aggressive fish such as other barbs, rasbora and loaches. It needs at least six but a few more would be better; slow or sedate fish will be annoyed by all this species' activity (not that you're suggesting such, just mentioning for benefit of whomever).
I personally would not risk them with such nippy fish as Serpae or Black Skirt Tetras, and in any case a 35g is insufficient space for anything but the two tetras so long as they are there. As for the Tiger Barb, in a 4-foot tank of at least 55g it might be OK, with a group of 15 TB so they are less inclined to look outside their own species for their trouble-making.
It is an active shoaling fish so the tank must provide adequate swimming room. The colour will be more intense if the aquarium has a dark substrate, with plants around the sides and back, and minimal light (which can partly be achieved with floating plants). Keeping the fish in a group of six or preferably more will also intensify the colouration as the fish interact within the group. The fish move around the aquarium but tend to remain close to the middle in the water column. Males are brightly coloured with orange-red on the flanks and the fin markings are more defined, while on females the flank colouration is confined to the caudal peduncle and lightly in the ventral fins; the female is rounder in shape. I found the photos below, the male is the colourful one and the other is a female.
