Kalanidhi Yoga makes a person intelligent, fearless, instills commendable qualities and good habits, noble lineage. It increases sexual appetite. It can be of two types:
1) Jupiter in the 2nd or 5th houses with Venus or Mercury, or under the aspect of one of these planets;
2) Jupiter in the 2nd or 5th house in a Mercury or Venus sign.
Sri Govind Swarup Agarwal - "Vedic Astrology"