Originally Posted by locksmith
No live plants. But looks like the tank has now cycled, Ammonia is 0 and so is Nitrites. When is it ok to introduce new fish ??? Can I do it now ??? Have three Tiger Barbs @ the moment. At what pace do you add new fish ??? Over what period of time ??? Whats the time required between each time you add fish ???
Thanks again everyone for your advice, been great. I find Aquarium Shops to money driven and they don't give the correct advice.
Once an aquarium is cycled, it means the nitrifying bacteria are present at a level to handle the ammonia being produced at that point. Bacteria will always be at this level, to handle the available ammonia (and subsequent nitrite obviously). If the ammonia decreases, the bacteria go into a sort of suspended state or die off, and if it increases they will multiply which takes up to 20 hours. Depending upon the tank volume, fish must be added slowly so as to not suddenly increase the ammonia. And this is solely dependent upon the tank size, type of fish, water parameters and if live plants are present which they are not in this case. You can read about this in detail here: http://www.tropicalfishkeeping.com/f...quarium-74891/
You have a 70 litre (roughly 20 gallon) tank, so I would add fish at maybe 3 at one time in the case of barbs. With tiger barb, I would not have other fish in this tank. As their profile mentions [click the shaded name], this species is prone to aggressive nipping, and a group of 8 is recommended minimum to keep the aggression within the group, and that should be in a 30g tank. In a 20g it will be a risk as the space is less than what the fish really should have.