questions: asked about ground water trewatment for fish farming and fish combination for farming 
 answers: for ground water treatment: rapid aeration can be done or application of alum
plgease consult fisheries department
6 species combionation: catla  @ 2000, rohu@ 2000, silver carp @ 1200, grass carp @ 800, mrigal @ 1200 and common carp @ 800 per hactare
3 sepcies combination catla @ 3200, rohu @ 3200 and mrigal @ 1600 per hactare