Originally Posted by Eliedaoura
Ok il do that . But is that happening cause the aquarium is new ??
Yes it is. In a new tank/filter there is no bacteria to consume the ammonia your fish produce so it builds up to toxic levels. Some bacteria slowly start to grow (mostly in the filter) and consume/eat the ammonia turning it into nitrIte. Then the nitrIte builds up to toxic levels as a second kind of bacteria grows and consumes the nitrIte tuning it into nitrAte. The nitrAte is then removed with weekly water changes.
The whole process takes 4-8 weeks (sometimes longer).