And a clown pleco...
I'd speculate that the Tiger barb is only being laid back due to stress, as a result of poor water quality as associated with a fish-in cycle
When the cycle completes and the Barb's behavior returns to normal, the Guppy will likely be shredded
That is in the un-likely event that the Guppy makes it through the cycle
Tiger barbs need a minimum group of 4, with 6 being better. The larger the group, the less nippy they get. They would be OK in a 60l IMO, but in a recomended group of 6, they would have the tank fully (and dibatably over) stocked at 2 inches per gallon
The Guppies needs and requirements are well covered above by Davo above.
The Guppy will likely go over in the cycle, so that may be of little concern to you unless you want to rescue it and get it re-homed ASAP. After that, you need to decide whether or not to keep the tiger barbs, or to keep the danios and get Neons to go with. If the latter, you will have to up the numbers to 6 for each to keep them happy, and you can then call the tank stocked, or overstocked again at 2" per gallon
I'd advise waiting untill the tank is 6 months old before adding neons, for the same reason as waiting for guppies. No doubt you saw the post explaining why, and hence why this thread started?
All the best
Rabbut
EDIT to add, Dwarf Gourami are nice, but need to be ket lone male, or trio (1M2F) to avoid agression. they are nippy, and would need to replace the Tetras or Danios in your final stocking... They will not work with the Tiger Barbs, due to overstocking, or Guppies though, as they are nippy...
