Though it's true that a dwarf (colisa lalia) would eat guppy fry, it would actualy be a suitable addition to your tank and would not eat all the fry or, in fact, any more fry than what the fish you already have would claim. Males are more territorial (the blue one would have been male - they also come in striped and orange colors - females are duller) but not to the same extent as the three-spot I initialy assumed it to be. They are usualy harmless to other species of fish, only showing aggression towards their own kind or closely related fish. They also stay at around 2" so are much smaller than the 6" three-spots. The major downside to this species of gourami is that mass-production and inbreeding have taken their toll and most now carry disease or are highly susceptible to internal bacterial infections (and, thus, dropsy aand ulcers are common). You probably made the right decision not buying it regardless as you should never buy any kind of gourami on impulse. They are not usualy forgiving.