The Collaborative International Dictionary of English v.0.48:

fishpond \fishpond\ n.
   a freshwater pond with fish.
   [WordNet 1.5]

WordNet (r) 3.0 (2006):

fishpond
    n 1: a freshwater pond with fish

Moby Thesaurus II by Grady Ward, 1.0:

46 Moby Thesaurus words for "fishpond":
   aquarium, artificial lake, bayou lake, cistern, dam, dead water,
   dike, etang, farm pond, freshwater lake, glacial lake, inland sea,
   lagoon, laguna, lake, lakelet, landlocked water, linn, loch, lough,
   mere, millpond, millpool, nyanza, oxbow lake, plash, pond, pondlet,
   pool, puddle, reservoir, salina, salt pond, stagnant water,
   standing water, still water, sump, tank, tarn, terrarium,
   tidal pond, vivarium, volcanic lake, water hole, water pocket,
   well