what's wrong with my fish?

[TanCH]

I've recently got a pair of apisto. agassizii "tefe" as a b'day gift. But the male fish is always swimming (dragging) at the bottom of the tank, and it seems to have difficultity swimming upwards freely. But the colouration and fins all seems perfect. What's wrong with my fish?

[barmby]

Is the fish ok now? It could be somehow troubled by Whitespot Disease or the fish is stressed from another male's abuse. the fish is definitely stressed else it won't behave strangely.

[TanCH]

I've seperated the male from the main tank and medicine is given for a week now. Everything seems fine but it just can't swim properly..