Visas are only required by the following countries.
Afghanistan, Albania, Algeria, Angola, Armenia, Bangladesh, Bosnia-Herzegovina, China, Congo (Democratic), Congo(Republic), Cuba, East Timor, Eritrea, Ethiopia, Ghana, Haiti, India, Indonesia, Iran, Iraq, Jordan, Laos, Lebanon, Liberia, Libya, Mali, Mongolia, Mozambique, Nepal, Nigeria, North Korea, Pakistan, Palestine, Sierra Leone, Somalia, Sri Lanka, Sudan, Syria, Vietnam and Yemen.
Everyone else gets 30 days or more at the border or airport.
Nicaragua visa requirements
Nicaraguan Embassies - Consulates and Missions