Gold Fish Are Dying

[rasna]

I am new to this world. I have this water fountain ( W=80cm, H=20cm , Depth=80cm) of 33 USA Gallons.
I have enough oxygen , as water get pumped and fall back in the fountain, I also have oxygen air pump and two submerged (sponge based) water filter.
Water PH is around 8 to 8.2, I am using the anti chlorine, and I have tested for ammonia and NO2 both are zero values.
I change water once a week.
I have 8 gold fishes in this setup. I think I have oranda or lion head not sure, as I am still learning , I got this fishes last month on 23rd. everyone was ok it was perfect till yday
Yday night I found one lying down and wasn’t eating (it was ok yday) this morning I found him dead.
Today when I pay close look to other one it has same symptom and lying at the bottom and not eating food. And I did some google and for me it looks like it scales stick out ( I am so confused don’t know whether it is) and it is bloated. So I am wondering whether it is dropsy
And when I look closely at other gold fishes, it seems there scales are also sticking out ( bitt) and some where it is green, may be because it rubbing its body against the floor which has layer of algae ( because the fountain is exposed to sun light).
I feed twice a day , gold fish food.
I am wondering whether the tank (made of cement) is bit of porous and when I clean the bottom (when I scratch to remove the allege) the whit dust comes out so I am wondering whether the porous nature is creating any internal problem to the fish like dropsy/kidney failure.
Any help would be appreciated

 

[blinky000]

The general rule of thumb is 10 US gals per goldfish. Having 8 in a 33 gal means you're very overstocked. Any disease that enters your pond will spread like wildfire and if the scales are sticking out all over their bodies, it certainly sounds like dropsy. This is a catchy bacterial infection and unfortunately, there doesn't appear to be a cure. Adding salt at 0.3% can help but most efforts at curing it are futile. Another sign of dropsy can be bulging eyes. However, you say that it looks like the fish have green patches where they have been rubbing on the algae, do the scales stick out just around that site or all over? Do you have a photo of the affected fish?

Next, the cement can alter the pH of the water. A significant pH shift either up or down can kill goldfish so consider putting a liner in there to keep it stable. Also, it is quite a harsh surface for the fish to rub themselves on. It makes me wonder that if your fish have injuries from this that they may be flashing/flicking to "scratch" any microscopic parasites off. Are there any other symptoms like split fins or white spots?

Lastly, you said you don't know if you have an oranda or lionhead. Does it have a dorsal fin like this: http/www.google.co.uk/imgres?q=oranda&um=1&hl=en&safe=off&biw=1280&bih=899&tbm=isch&tbnid=dZPp7muqjmB4tM:&imgrefurl=http/www.aquariumfish.net/catalog_pages/goldfish_and_koi/oranda_table.htm&docid=TYLWQQ9nyZ5cOM&imgurl=http/www.aquariumfish.net/images_01/oranda_red_and_black.jpg&w=360&h=260&ei=3GqlTuWeI83u8QO54NjxAw&zoom=1&iact=hc&vpx=975&vpy=142&dur=5754&hovh=191&hovw=264&tx=95&ty=98&sig=107805264388237033402&page=1&tbnh=167&tbnw=202&start=0&ndsp=20&ved=1t:429,r:9,s:0
Or without like this: http/www.google.co.uk/imgres?q=lionhead+fish&num=10&um=1&hl=en&safe=off&biw=1280&bih=899&tbm=isch&tbnid=0S--yCKGTBsAeM:&imgrefurl=http/www.aquarticles.com/articles/travel/Norfolk_VAS_XII.html&docid=-S4qbdICZctliM&imgurl=http/www.aquarticles.com/images/Fish%252520Stores%252520Canada/NAPSI/p-44%252520Lionhead%252520d45%2525202x80.jpg&w=620&h=449&ei=KWulTqyONZSw8QOYmIHHBQ&zoom=1&iact=hc&vpx=398&vpy=402&dur=283&hovh=191&hovw=264&tx=81&ty=93&sig=107805264388237033402&sqi=2&page=1&tbnh=157&tbnw=209&start=0&ndsp=20&ved=1t:429,r:16,s:0