There is the Blue Gourami, though not what I would call "bright" blue. The Dwarf Gourami has been selectively bred to give a blue variety. And there may be a "blue" variety of Honey Gourami, not sure but I think I've seen this somewhere. There is some blue in other species but not overly blue, depending upon what you are intending by bright blue.
With a four-foot 70/75 gallon tank you could manage any of those mentioned, but not together. Male gourami are very territorial, much like cichlids, and they can be as rough. The Honey is relatively docile. The Dwarf is risky due to disease unless you get them direct from a reliable breeder. The Blue Gourami is the species Trichogaster trichopterus, sometimes seen under the former name Trichopodus trichopterus, and occurs in a variety of variations including the Blue Gourami, Gold Gourami, Three-Spot Gourami, Opaline Gourami, Cosby Gourami, and Marbled Gourami. There may be more. Being the same species, they should not be combined as the males will consider each other as rivals.
Most gourami are best kept in a small group with more females than males to allow the females some rest from the attentions of the male. One male with two or three females works well, or two males with four or five females (depending upon the species).
Although not especially "blue," one of the most beautiful gourami is the Pearl, Trichopodus leerii, and a group of these in your tank would be a beautiful sight indeed. Here I would go with two males and four or five females.
I would not add other gourami with T. trichopterus as this species can be quite nasty defending their tank. T. leerii is probably best on its own (as gourami) too. I have found that the smaller gourami species sometimes work well together, thinking here of the more rare species like the pygmy sparkling, chocolate, eyespot, licorice, etc. These are very delicate fish though (except perhaps for the pygmy sparkling). I had two species of chocolate in small groups, a trio of eyespot gourami, and a small group of pygmy sparkling in a 70g very heavily planted aquarium a few years back, and they all spawned regularly and managed to remain out of each other's way in the thick plants. And it was thick; no "swimming" room at all, which is ideal for gourami. But a group of Pearls or Blue are different, so long as there are floating plants.
Suitable tankmates include many of the rasbora species. These are more sedate fish (as opposed to active swimmers), and very peaceful. Barbs and danio are not good choices as they are all active swimmers and this will annoy the quiet gourami. For the lower level, some of the loaches work well. The smaller species, like the Dwarf Chain Loach, Dwarf Banded Loach, Angelicus Loach (Botia kubotai) or Zebra Loach (Botia strigata), in a group of five or six of one species. These do not get too large, and while they are somewhat active they are not up in the space of the gourami. Just avoid upper level fish that are active.
Byron.
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