Electrical woes...breaker box what??

[Myka]

Thanks for your reply James. We haven't tripped the main breaker, just the one the fish tank is on if I try to blow dry my hair on the same breaker.

That breaker is a 20 amp breaker, so would it be safe to assume I can have around 1900 watts on it at any given time? Is that all wall outlets combined on that breaker, or 1900 watts on each wall outlet of a 20 amp breaker?