His other fish are:
synspilum - 12+ inches
severums - 8+ inches
tinfoil barbs - 10-12 inches
All 3 get bigger than blood parrots which you say are too big for the tank, so no, none of the others can work either.
That's a bit overstated don't you think? Other then the synspilum and the tinfoils, severum or parrot would be pefectly fine in a 3 footer alone as adults. At the moment his Severum is 5", his parrot is 3" and his tinfoil is dead. If he removes the syn he can keep the other two for some time and then eventually choose one of them to keep.