no idea about tropical fish, ask the guy in your local shop, then get a second opinion elsewhere!
water changes;
tap water contains chlorine, and if you put that straight into your tank it will kill the bacteria in your filter, or that colonise the gravel above your under gravel filter. this is what will then kill your fish!
you can get chemicals to neutralise the chlorine, (which is ok as an emergency measure).
much prefer to get several buckets of water ready in the garden, at least 24hrs prior to water change, but 48hrs is better.
give bucket a good stir once or twice a day, the agitation helps, and the chlorine just disappears, magic...
be sure to not wash out filter, etc, in tap water, but save an extra bucket for this!
sorted...
