goldfish bio load question

[venzi]

Why do people claim that goldfish have high bioload (when compared to other freshwater fish)?  Isn't it basically if you feed the same sized fish the same amount of food, then the same amount of waste will result (roughly speaking)?  Does the goldfish have some kind of special metabolism or digestion process that produces more waste per unit of food consumed?

[Chick-In-Of-TheSea]

They do get big and they will also eat a lot of other stuff besides fish food. They will eat plants and they will also pick up gravel and eat the stuff off of it (ie: algae etc) and spit the gravel back out.  I imagine another factor to consider is that goldfish are cold water fish, whereas other aquarium fish are tropical fish that live and thrive in higher temps.  

Also found this:

Goldfish have the largest bioload of *almost* all aquarium fish. This is due in part to the lack of a prominent stomach, meaning food just goes in, and comes right back out. So a 12 inch adult goldfish would foul up a 12 gallon tank in a very short period of time.

Source: https://www.myaquariumclub.com/things-to-consider-when-stocking-an-aquarium-5837.html

Not sure how reputable the source is, but this may at least help point you in the right direction.

@Hannah Parker

[venzi]

Oh I think I've read that somewhere as well about food going in and just coming out.  I think it might be more applicable to fancy goldfish b/c of their compacted body size.  Comet and common goldfish I doubt would have the same issue.  Interesting.

[modified lung]

On 10/5/2022 at 1:34 PM, venzi said:

Comet and common goldfish I doubt would have the same issue

It's actually true of all goldfish and koi as well.

[Patrick_G]

I haven’t found my goldfish to produce a particularly heavy bioload. I have six in my 100 gallon outdoor patio pond and my average size filter keeps up without any problems. I bet the situation would be different if it was feeding more than once a day. 

[venzi]

On 10/5/2022 at 2:23 PM, Patrick_G said:

I bet the situation would be different if it was feeding more than once a day. 

Right.  I wonder if that has to do w/ the claim of higher bioload for goldfish.  Goldfish are considered beginner fish and new comers to fish keeping hobby will overfeed b/c goldfish will eat as much as they are given.  But I don't think this trait is unique to goldfish.  I think betta fishes do the same thing.

Edited October 5, 2022 by venzi

[Flumpweesel]

All I can add is that my two big goldfish (both fish exceeded 20cm in length) required more frequent water changes and filter cleaning than the same tank now it's a tropical community. 

I fed them about the same as feed the community. 

[modified lung]

On 10/5/2022 at 2:38 PM, venzi said:

Goldfish are considered beginner fish and new comers to fish keeping hobby will overfeed b/c goldfish will eat as much as they are given.  But I don't think this trait is unique to goldfish.  I think betta fishes do the same thing.

All true but goldfish probably won't die from over eating because of not having a true stomach. I heard a koi and goldfish farmer tell a story once about failing with his first attempt at guppies because he didn't realize they can't constantly eat like the fish he normally raised.

I'd guess the higher bioload thing mainly comes from goldfish constantly foraging for food and not being as picky about eating whatever they find compared to a lot of other fish. I had a small comet goldfish in a community tank for a while and they guy never took a break.

[gardenman]

In the aquaculture world, bioload is mostly determined by the weight of the fish. A six-inch-long goldfish will weigh more than a six-inch-long swordtail. There's a complicated series of schedules that revolve around the weight of the fish, the weight of the food, composition of the food, the water temperature, and more to determine the bioload, but in general, the bulkier a fish is, the bigger the bioload is. 

Those on the lunatic fringe of the koi world who want the largest possible koi will feed their koi nonstop using an auto-feeder with a trigger (typically a ball or lever) that the fish can hit whenever it wants food. And they want food a lot. They need insane filtration to keep up with the bioload of free-feeding fish.

[venzi]

On 10/6/2022 at 6:12 AM, gardenman said:

Those on the lunatic fringe of the koi world who want the largest possible koi will feed their koi nonstop using an auto-feeder with a trigger (typically a ball or lever) that the fish can hit whenever it wants food. And they want food a lot.

WOW!

 

On 10/6/2022 at 6:12 AM, gardenman said:

complicated series of schedules

What do you mean by "schedules"?  Do you know of any links/resources or the exact term to google search to find out more details?