(07-01-2013, 04:47 AM)TheBrit Wrote: Bettafish, Siamese Fighting Fish are tolerant of quite large changes in water quality. However no aquarium, coldwater, freshwater tropical or marine should have any large water changes, 25% weekly is more than adequate unless the tank is grossly overstocked. Even if the tank is undergoing major maintainance, or has to be moved, the substrate should be removed and rinsed in aquarium water. At least 60-70% should be kept in buckets and then replaced into the aquarium with new water being gradually added.
I have to respectfully disagree.
As a species of tropical fish, betta is as fragile as most other tropical fish when it comes to large change in the water perimeter. Many novice fish keepers have reported betta become sick or dead after "water change". Almost all of them have made the mistake of did either 100% or very large percentage water change.
If you keep up weekly partial water change of no more than 50%, as long as you do not overfeed or have too small of a fish tank, the water quality shouldn't go down much. Another 50% partial water change won't bring significant change unless you skipped too many weeks without maintenance.
The key with water change for tropical aquarium is, you need to make sure the temperature of the new water need to be as close as possible to the tank water. Temperature shock is very dangerous to all tropical fish. Betta (Siamese fighter fish) is no different in this case.
