More likely  Rudd also goldfish will soon revert back their natural bright olive colours which are very different to Rudd so almost certainly them. 

I have seen them in some venues where they would be 3lb especially where they get a free feed from the families who feed the ducks.

Deep alright. The American army in the region dumped all there vehicles and ammunition etc on the bottom when they bailed after the 2nd world war so yeah theres couple of snags in there. The old fulla that used to man the place told me there was rudd, tench perch and carp in there. I took the carp bit with plenty of skepticism, but maybe there is a few grassies in there.

I don't know what they were but one day I saw about 3 fish about 1-2kg size sitting on the bottem in about 4m of water. I thort they were trout at the time, but then put it down to tench. I also saw one rise up to the surface one day about 1kg before ducking back down. The only other fish I have seen in there is what I think are Rudd, from the surface they look like a stiped bronze and dark brown/grey colour. Caught a few on the fly rod one day just little ones on a black wolly bugger. I have also done some free diving there, it is a very spooky place that goes down in shelves, The first of which is about 3m, second about 6, third about 9 and at that point it looked to go down from there, god knows how far but I chicken ****ted out at that stage!!! I think in the deep point its about 25 metres, heaps of rumers going around sayign 50-80m but thats bull cruds IMO. Know some guys that actually tanked it one day and they said that you get to a certain point and then the vis shuts down completly, then silt, then soft mud, then thicker and thicker untill god knows what. Oh, and heaps of eels. 

A couple of years ago, I fought my way through the overgrowth down the far end, and peering into the water there were two big carp that would have been close to double figures basking in the shallows close to a reed bed. They had no colouration and largish scales, so could have been Grass Carp, although they looked deeper and stockier than Grass Carp. However, looking into water at an angle can be deceptive, so I couldnt say. Never did get back there to fish.

I'd +1 the opinion that the large scaled fish will be carp.

The Tench are likely to get to a good size though, used to see plenty of big buggers cruising the Waitangi River up from Haruru Falls.

there was a white foamy froth around the edge of the lake...

Wouldn't be concerned about that, this time of year most likely to be from pollen.  Lake Taupo shoreline foams up bad when the pollen is coming off the pines like smoke but it's harmless.

Jeez, that is deep. I won't be going to reach the bottom anytime soon.

Caught a nice grass carp at Parkinson’s Lake, near Waiuku

Funnily enough I was fly fishing and it was on a buzzer fly hard on the bottom - I think the carp just sucked it up accidentally!

by the way I was just using a small minnow type softbait lure and also caught one of the perch using a worm livebait, they were small perch but they were coming right up to shore probably hunting the minnows and common bully’s. Also how big do the perch there get?