Recently, we successfully used P. guajava supplemented fish
diets to control A. hydrophila infection in tilapia (O. niloticus). This
work encouraged us to look for a plant with prophylactic and/or
therapeutic effects against fish streptococcosis caused by S. agalactiae.
In this study, six herbs (A. sativum, A. paniculata, C. alata, G.
mangostana, P. guajava, and S. asper) were evaluated for their
antimicrobial activity against S. agalactiae. The herbs were selected
because they are distributed throughout Thailand and have been
reported to have antimicrobial activity (8–17).