Out of general interest and natural concern for my system, I took the liberty of contacting the WaterCorp to inquire about the use of chlorine and/or chloramine in my local water supply (Mt Hawthorn, which I would assume would be pumped from the reservoir atop Joondanna/Tuart Hill).
I was most pleased to recieve a personal reply from their Customer Care people, who were quick to allay any fears about chloramines in the local supply.
Their reply - and I quote:
"I can say that there is no chloramines in your drinking water but, there is chlorine and it would be about 0.30mgl or ppm and at times get to about 0.45mgl with this cold weather chlorine its getting to the houses at these levels and the readings I have given you are from the sample point in the Mt Hawthorn area.
Also in the attachment below is a copy of the drinking water quality data sheet for the Mt Hawthorn reservoir I hope this helps."
The attachment he speaks of is a .pdf outlining the water assay of the Mt Hawthorn area. I'm happy to email it to anyone interested?
The WaterCorp also has an information booklet titled 'Water Quality Issues - Chlorimation of Water Supply in Western Australia - Implications for Maintenance of Fish Ponds and Aquariums'
That publication may be found
For your information!
BT
I suggested that them chemicals are not compatible with edible fish, I'm not a scientist but as chloramine is ammonia based I would have thought it would cycle out 
but problem would be when topping up, the link above suggests that keeping pH below 7 also counteracts it, but we know the higher the pH, less ammonia system can handle