Tank is 50 gallon
two red oranda; one red cap oranda; black moor
Approx 4 months old tank.
50 - 75mg/l NO3
Oxygenated by one 3" air stone with an external pump, plus one filter pump (right size for tank) fixed to side wall. 5 oxygenater plants on gravel bed (over a filter tray - which we should maybe remove as its not in use?)
Syphon bed weekly and perform 10% water change. Got a little slack last week as first change for two weeks. Use Safe Guard (UK) weekly (20ml) and a de-chlorinator on the 10% fresh water.
As mentioned fish is acting normal, although now a little paranoid and watching its every move. Black mark on tail fin appeared couple of weeks ago, now spreading along fin and towards base of fin (where it joins the body). Also noticed a small development on her top fin.
Hope that helps