If you say that someone is fishingfor information or praise, you disapprove of the fact that they are trying to get it from someone in an indirect way.
If you tell someone that there are plenty more fish in the sea, you are comforting them by saying that although their relationship with someone has failed, there are many other people they can have relationships with.
PHRASAL VERB
(从…中)取出,拿出,拖出
If you fish something out from somewhere, you take or pull it out, often after searching for it for some time.