Yes you can cycle the tank with 9 danios butTony said:HI, All Setup a new tank 210L 46gallon a week ago using a fluval ext 3 filter containing bio-max and carbon.
i have put 9 danios in the tank all levels are at 0 ammonia, nitrate .PH 7.2 feeding twice a day. My question is there enough fish in to cycle the tank.
the cycle period may be greater than 28 days and
the danios may not be happy fish if the ammonia and nitrites rise very, very slowly before they peak (your post indicated nitrates but I believe you meant nitrites).
I cycled my 110G tank with 12 guppies, seven cories and 6 gold nuggets.
I fed very little and barely observed an ammonia and subsequent nitrite concentration.
The ammonia concentration was not detectable at 14 days and the nitrite concentration was not detectable at 21 days.