Hello I'm currently cycling my new 210 Gallon fish tank and would be housing fancy Goldfish in it. I would like to know how many Goldfish I can stock in the tank? Here are a few details about the tank: Dimensions: 84" (L) X 24" (H) X 24" (W) Tank Material: Glass (12mm) Filtration: 2 X SunSun 304A + 1 X SunSun 302 (Will also be adding an Eheim 2217 soon) + XY-380 Sponge Filters X 4. Water Change: 40% Weekly. For water movement inside the tank I'm currently using a Sobo WP-2550 powerhead (rated @ 2,800 l/hr) Water Temperature: 28C (Ambient) This will be a bare-bottom tank. This is a photograph of the tank itself: https://s3.postimg.org/fb3p98on7/DSCF5595.jpg Kindly advice. Regards, tintin1982

In a 210 gallon, 12-13 Fancy goldfish would be good IMO. Btw it's going to look stunning , I currently have 5 Fancy Goldfish, Beautiful fish with lots of personality. Good luck!!

If your talking common gold fish i say 0. If these are fan tail gold fish around 17 max with good filtration.

The OP stated Fancy goldfish but 17 Fancy Goldfish in a 210 gallon aquarium?? Orandas get 8-9"...IMO that's over stocking even with amazing filtration. I wouldn't do more then 12-13 Fancy Goldfish in a 210g , and thats only giving each goldfish 16g of water to themself.

Sorry I missed the fancy part. 17 would be max,IMO, but its never a good idea to max your tanks stock. Rule of thumb on these guys is 30 gallons for 1, 10 additional gallons for each additional.

Thank-you so much for the replies, really appreciate it! Having read the input I decided that I will be stocking the tank with 12-14 fishes. No more. This is the filtration that I have: 2 X SunSun 304A Canister 1 X SunSun 302 Canister 1 X Eheim 2217 Canister (will be receiving it soon) 4 X XY380 Sponge Filters 1 X SunSun 603B (I know this only adds little to the overall filtration of the entire water volume but it's currently housing cycled media and I have it coupled with an overhead sump box with bio-balls. Basically the water from the canister empties into the sump box filled with the bio-balls and then finally from that sump box returns to the tank). 1 X Sobo Powerhead with another overhead sump box filled with Seachem Matrix. (The canisters will be filled with ceramic rings, filter sponge and scrubbies).

Hi Dave, These are the filter details: 2X SunSun 304A @ 423 Gallons/Hr (each) 1 X SunSun 302 Canister @ 264 Gallons Per Hour 1 X SunSun 603B @ 106 Gallons Per Hour 1 X Sobo Powerhead with another overhead sump box filled with Seachem Matrix: The Powerhead is rated @ 740 Gallons Per Hour. 4 X XY380 Sponge Filters - These are the largest sponge filters I could find. They are 2 Hagen Marina 200 Air Pumps. This also brings me to my next question... Do I need to fit the Eheim 2217 in the tank or should I refrain from doing so? With the above filtration I'm thinking I should be ok without immediately connecting the 2217?

with canister filters you'll want to shoot for atleast 1150gal/h of filtration for your 210g. The rule of thumb is 5-6× the amount of gallons but with Goldfish being that they have a big bio-load I would aim for slightly higher.

I'm not familiar with that kind of filter but I like the GPH its around 1500 total + the sponge filters.