Barb

Fin-nipping in barbs is usually a sign of a group that is too small or of tankmates that are a poor match rather than a fixed trait of the species. Many popular barbs, especially the tiger barb, are active schooling fish that naturally chase and playfully nip at each other within a school as part of normal social behaviour, and when kept in too few numbers, often fewer than six, that same energy gets redirected at other fish in the tank, particularly slow-moving species with long, trailing fins such as angelfish or bettas. Keeping barbs in a proper school of eight or more, and avoiding very slow long-finned tankmates, greatly reduces the problem.

Both are small, popular, schooling aquarium fish, but they come from different families. Barbs are cyprinids, the same large family as carp, goldfish, and minnows, generally have barbels around the mouth, and tend to be somewhat more active and boisterous swimmers. Tetras are characins, the family that also includes piranhas, generally lack barbels, and are typically a bit more delicate, favouring softer, more acidic water than most barbs, which tolerate a wider and often harder water range. In practice barbs are usually hardier and better suited to a beginner's tap water, while tetras often need softer water to thrive and colour up fully.

At least six, and eight or more is better for the more boisterous species such as the tiger barb. Barbs are schooling fish, and a small group leaves individuals anxious, prone to hiding, and, in more aggressive species, likely to take out excess energy on other tank inhabitants through fin-nipping. A larger, well-established school spreads normal chasing and sparring behaviour within the group, produces calmer and more confident fish, and is also simply more attractive to watch, since a big group of barbs schooling and flashing together is one of the more dynamic sights in a community tank.

No, size and temperament vary a great deal across the fish loosely called barbs. Small species such as the cherry barb and the rosy barb are generally peaceful and suit most community tanks. The tiger barb is more boisterous and best kept in a larger school with robust tankmates, avoiding slow, long-finned fish. Some larger barbs, including the tinfoil barb, grow to 30 centimetres or more and need a very large aquarium, effectively ruling them out of a typical community setup, so it is worth checking the adult size and temperament of a specific barb species before buying rather than assuming all barbs behave the same way.