What size is your tank?
Tiger Barbs will do better in a longer length tank than a tall tank. Would suggest a tank length of at least 2.5 - 3+ feet.
Groups minimum of 12, the more the better as this helps to spread their aggressiveness, and yes they can be very aggressive.
These species are one of the nippiest and aggressive that I know of, and have heard some stories about them that will make you go
But I think a lot depends on the temperament of the group of tigers, some are more aggressive than others, they will certainly be likely to fin nip at any fish species with long fins, and if they are aggressive at all then they will likely nip at most fish species including cories and plecos.
You might get lucky and have a placid group of tigers.
So this kind of makes the tiger barbs hit or miss to mix with cories.
Personally I would keep them as a specie only in a biotope type tank, as they are a very nice looking and interesting fish specie imho, though must admit I prefer the natural colouration to the green ones.
Quote from SF -
"This species is notoriously aggressive with a reputation for biting the fins of other fishes, although this behaviour only seems to be pronounced when insufficient numbers are purchased or space is limited.
That said, it is relatively boisterous and does not make an ideal companion for timid, slow-moving, or long-finned species such as many livebearers, cichlids, and anabantoids.
Robust fishes inhabiting similar biotopes in nature, especially comparably-sized, pelagic cyprinids perhaps constitute the best choices but other options include balitorid, cobitid, and nemacheilid loaches as well as benthic cyprinids such as Crossocheilus or Garra species. If geography is not an issue many rainbowfishes and tetras are also suitable, but be sure to research your choices thoroughly before purchase.
It is a gregarious species forming loose hierarchies, with rival males continually battling with each other for female attention and hierarchical position within the group.
A group of at least 8-10 specimens should be considered the minimum purchase since this increases the likelihood that the fish will be distracted by each other rather than their tankmates and will result in a more natural-looking display. Males will also show better colouration in the presence of conspecific rivals."
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