Fifth House is the house of Knowledge, the house of Popularity and the house of Children. Jupiter is the planet which signifies abundance. Jupiter in Fifth House makes a native have sound knowledge, be popular among others as well as have good and obedient children.  

     Jupiter is at home in the Fifth House. Jupiter from Fifth House casts an aspect on Ascendant which defines the character and physical traits of an individual. Due to the aspect of Jupiter native is blessed with a calm and composed character. As long as there are no negative aspect or placements in Ascendant the native becomes kind, considerate and helpful individual who is an asset to the society. Physically there are chances of becoming obese but normally native is tall and attractive with an even better personality. From Fifth House placement the other aspect of Jupiter is on the Ninth House which is the house of Fortune, Forefathers, Higher Studies as well as Long Distance Travels. Native can get good gains from long distance travels. Native is born in a family which has a glorious legacy. Also native himself is fortunate and can be successful in all his undertakings. Jupiter's aspect on Eleventh House gives native income via multiple means as well as have good and loyal friends. Also he/she is part of huge social circle and is good in networking skills.

     Jupiter in Fifth House gives fame and native is well-known in the society. Native generally receives positive fame unless there are other malefics which negate effects of Jupiter. Jupiter also gives good, obedient and healthy children who are a source of pride for the native. In Stock Markets native can gain via Planned Investments. Native is advised to stay away from gambling. Jupiter hates shortcuts and prefers long, enduring and carefully thought about Investments Plans. 

      According to B. V. Raman: "Jupiter in Fifth House makes one possess logic and be highly intelligent.  Also he can command good knowledge over law and religous practices. He is likely to be a instructor, diplomat or advisor in government role. Native would possess good friends and vehicles as well as good manners. He has good progeny, is God fearing and posseses loyal and helpful friends."

     Jupiter in Fifth House is indeed a blessing to have. If there are malefics or bad aspects then native is advised to pray to Lord Vishnu and chant the Vishnu Sahastranam. If native is obese then he/she is advised to eat lots and lots of yellow lentils and drink juice of Bottle Gourd(Lauki) to stay fit and slim. Pranayam especially Kapal Bhati and twelve poses of Surya Namaskar would help stay fit and slim. 

References:
Raman, Bangalore Venkata. How to Judge a Horoscope. Delhi: Motilal Banarsidass, 2014. Print.