Is bioload just the amount of food you feed your tank?

[Galabar]

I had been thinking about this for a while, and the recent AOC video reinforced the idea for me: is the bioload in your tank just the amount of food you feed?

Your fish my "absorb" a small amount of the food to themselves as weight.  However, it seems that most food will eventually be broken down into ammonia (either by the inhabitants or just through rotting).

We hear about fish that are extra "dirty."  However, I don't think fish can break the laws of physics ("In this house, we obey the laws of thermodynamics!").  If you don't feed your goldfish or pleco very much, they aren't going to generate "extra" waste.  If you feed your chili rasboras a lot, they might not eat it all, but it will end up as ammonia (eventually). 🙂

[Lennie]

Science peeps may comment on this further, but as far as I know, freshwater fish mainly release ammonia from their gills, not poop. If bioload is the nitrogen processing demand, then I guess it is not the food alone.

[Galabar]

On 8/29/2023 at 11:13 PM, Lennie said:

Science peeps may comment on this further, but as far as I know, freshwater fish mainly release ammonia from their gills, not poop. If bioload is the nitrogen processing demand, then I guess it is not the food alone.

The "fuel" would need to come from an energy source (the food), unless the fish were losing weight.

[nabokovfan87]

There was a talk from a fish vet on the co-op members only side and she had explained where ammonia comes from in the tank.

Needless to say it isn't just from food. The stat was something along the lines of 70% is from fish respiration.

I don't have access to it, but I highly recommend viewing that if you do have access or get a month for free as a gift. It's a great hour or two and will help with your care of the fish in future.

https://www.fdacs.gov/Consumer-Resources/Recreation-and-Leisure/Aquarium-Fish/Aquarium-Water-Quality-Nitrogen-Cycle

The majority of ammonia from fish is excreted through the gills, with relatively little being lost through urine and feces. Ammonia is also formed as uneaten feed or other organic matter in an aquarium decomposes.

https://edis.ifas.ufl.edu/publication/FA031

In fish, the majority of ammonia is eliminated from the body primarily by diffusion through the fish’s gills into the water. Smaller amounts are excreted in the urine or across other tissues.

Fertilizers and the decay of uneaten feed and organic matter contribute to ammonia, but in most aquaculture or hobbyist systems, the digestion of the feed eaten by the fish is the primary source of the compound. The more feed a fish is fed, the more ammonia the fish will produce. However, even a starved fish will produce some ammonia.

[Galabar]

I don't think how the fish emits ammonia is the issue.  The fish must respirate, taking energy from the food that it eats.  No food, and the fish will continue to respirate, consuming whatever stored energy it has (until it dies).

In a steady state, where the fish isn't adding weight, it is food in, and energy (and ammonia) out.

So, I guess bioload is (in a steady state) the amount of food added to the tank.

 

[Flumpweesel]

The dirty fish idea is a misnomer in my opinion but it is a simple way to explain that some fish will need more attention than others.  If you fed one tetra the same volume of food as one goldfish in the same size tank ect  you would probably see the  water behave very similarly. Although a hungry goldfish will trash your decor. 

This is why if you ghost feed to seed a tank you need to do it to match the planned population 

[Galabar]

On 8/30/2023 at 4:44 AM, Pepere said:

Of course the fish could be one that eats plants happily….  
 

in which case the inputs would be light, co2 and ferts…

Indeed.  You could imagine a tank that you don't feed at all, with all energy input coming from light.  In that case you might say that the bioload is zero...

[Galabar]

On 8/30/2023 at 11:02 AM, Pepere said:

Well, the livestock will still be releasing ammonia to the tank consistent with their metabolism….  The plants and bacteria would metabolize the ammonia away and use it for growth along with added ferts….

 

in essence you still have a bioload in the tank even though you are not technically adding food, but rather fertilizer…

To me, bioload is input and output.  For a closed system, you can consider the bioload zero.  I think this makes sense, as aquarist we worry about feeding, changing water, removing excess plant growth.  We also worry about the types of filtration need, given the bioload.

[_Eric_]

On 8/30/2023 at 1:09 PM, Galabar said:

To me, bioload is input and output.  For a closed system, you can consider the bioload zero.  I think this makes sense, as aquarist we worry about feeding, changing water, removing excess plant growth.  We also worry about the types of filtration need, given the bioload.

That is not a correct way to look at bioload.  Your fish are adding load and would require filtration whether you feed them or not.

 

[Galabar]

On 8/30/2023 at 12:47 PM, _Eric_ said:

That is not a correct way to look at bioload.  Your fish are adding load and would require filtration whether you feed them or not.

 

Actually, if you aren't feeding your fish, you would probably not need filtration.

[TOtrees]

Great discussion. No way will we all be in agreement on this. 😛

I think of bioload as pressure. How much pressure is being added? To what? For me what's being pressured [or loaded, as in bioload] is the tank's capacity to process [food/waste/etc] and return to a balance point. 

If I ask someone what sort of bioload they have in their tank, I'm asking how many/what size fish there are, how much they eat, and what sort of filtration/water change they run. 

 

[Galabar]

On 8/30/2023 at 12:55 PM, TOtrees said:

Great discussion. No way will we all be in agreement on this. 😛

I think of bioload as pressure. How much pressure is being added? To what? For me what's being pressured [or loaded, as in bioload] is the tank's capacity to process [food/waste/etc] and return to a balance point. 

If I ask someone what sort of bioload they have in their tank, I'm asking how many/what size fish there are, how much they eat, and what sort of filtration/water change they run. 

 

"pressure" -- I like that idea. 🙂

[_Eric_]

On 8/30/2023 at 2:50 PM, Galabar said:

Actually, if you aren't feeding your fish, you would probably not need filtration.

Well you can’t say I’m going to put fish in an uncycled tank for a week and think they will be fine because you don’t plan to feed them in that tank.  Fish won’t starve in a week but they will still generate a lot of ammonia despite the lack of food.

[Galabar]

On 8/30/2023 at 1:15 PM, _Eric_ said:

Well you can’t say I’m going to put fish in an uncycled tank for a week and think they will be fine because you don’t plan to feed them in that tank.  Fish won’t starve in a week but they will still generate a lot of ammonia despite the lack of food.

Yes, no one would or has said that.

[_Eric_]

Gotcha.  I misunderstood.  I thought you were linking bioload solely with the amount of food being put in the tank.

[Galabar]

On 8/30/2023 at 1:28 PM, _Eric_ said:

Gotcha.  I misunderstood.  I thought you were linking bioload solely with the amount of food being put in the tank.

I think it's mostly food in and plant matter out with some water changes (for planted tanks).  Or food in and large water changes out (for non-planted tanks).