Usage patterns
〈場所〉で鯉を飼うto keep/raise carp (at a place, e.g. a pond)
I keep carp in the pond in my garden.
鯉に餌をやるto feed the carp
The children are feeding the carp in the pond.
鯉が跳ねるfor a carp to jump/splash
There was a splash as a carp jumped near the surface.
Expressions
俎上の鯉someone doomed to their fate; fish on the chopping board まな板の鯉someone doomed to their fate; fish on a chopping board まな板の上の鯉someone doomed to their fate; fish on the chopping board (lit.)