Warm water for a fish that never sits still
Tiger barbs come from warm, slow-moving streams and swampy margins, and everything about them, their constant motion, bold feeding and tight schooling, runs on warm water. Keep the tank between 74 and 79 degrees Fahrenheit, with around 76 to 77 degrees a good everyday setting for a community aquarium. Their pH comfort zone runs from 6.0 to 7.0, and healthy, settled barbs will also manage water a little above that, up to roughly 7.5, provided nothing swings. Very soft water is not required; ordinary treated tap water inside that pH band suits the vast majority of home-kept tiger barbs.
What happens outside the comfort zone
Let the temperature slide into the low seventies and a tiger barb school changes character: feeding slows, colours wash out, and the bickering that a big group normally spreads around concentrates on the weakest fish. Push the water too warm for weeks on end and oxygen levels fall just as their metabolism demands more of it, leaving the barbs restless at the surface. Acidity swings are the other quiet problem, because a pH that drops after a large water change and climbs back between them keeps the fish perpetually adjusting instead of settling into routine.
Holding the range without fuss
Size the heater honestly for the room the tank sits in, since an undersized heater in a cold room runs constantly and still loses ground overnight. Confirm the temperature with a thermometer at the far end of the tank from the heater, and glance at it during feeding, when you are already watching the fish. Keep water changes moderate and regular rather than huge and occasional, and always treat and roughly temperature-match the new water first, which protects pH stability at the same time. A simple weekly note of temperature and pH builds a picture of drift long before it becomes a problem the fish have to show you.
Settling new barbs into your water
New tiger barbs arrive from shop water that rarely matches yours exactly, so the journey between the two matters as much as the destination figures. Float the bag to equalise temperature, then mix small amounts of tank water in gradually before release, giving the fish time to adjust to your pH rather than meeting it in one step. Test your tank on the morning of a planned purchase, not after the fish are home, so a drifted heater or a slipped pH is found while it is still a maintenance job. For the first week, watch feeding and colour at the same times each day; barbs that settle quickly into the school and feed boldly are telling you the water suits them.
Reading the school as your early warning
Tiger barbs announce water trouble behaviourally: a settled school cruises the middle of the tank together, while a stressed one scatters, pales or hangs listlessly under the surface. Treat a whole-school change as a water question first, test both temperature and pH, and correct anything you find in small steps over hours rather than minutes. That measured approach is worth keeping when the figures need a second look. Put a follow-up question to KinsLe's Kinny; he answers using the KinsLe Answers library.