How many goldfish to add

[Ariel Scott]

Hello,

     So I have a 35 gallon tank and growbed and fully cycled my system about a month ago.  I added 4 small goldfish to the tank about 3 weeks ago and they all seem to be doing fine.  I was wondering if I should add  a couple more fish.

When I test the ammonia its usually between 0 and .15 so the bio-filter seems to be handling the waste just fine.  When I test for Nitrates its usually around 0 so I'm wondering if I need to add more fish or if the nitrates will increase as the fish grow.

Thanks

[Harold Sukhbir]

Hi Ariel,

Yea, 4 fish seems very little and will take a longer time to cycle the system. 1 fish per gallon will be a conservative figure.

Your system is most probably not cycled as yet, so beside Nitrate, you'll be short on Nutrient for your plants as well.

[Ariel Scott]

1 fish per gallon would be 35 fish, that seems way to high.  I thought the recommended number was 1 fish per 5 gallons which would put me at around 6-7 fish.  The system was already cycled before I added fish and I have a pretty good amount of plants so I figured they are consuming all the nitrates being produced.

Harold Sukhbir said:

Hi Ariel,

Yea, 4 fish seems very little and will take a longer time to cycle the system. 1 fish per gallon will be a conservative figure.

Your system is most probably not cycled as yet, so beside Nitrate, you'll be short on Nutrient for your plants as well.

[Harold Sukhbir]

Hi Ariel,

The ratios from the rules of thumb are 1 lb of fish per 4 gallons water. As gold fish are smaller you can increase the numbers as long as you don't go over the ratios, which in your case should be approx 9 lbs of fish. So the system was cycled beforehand, great!

More fish means more fish feed, means more nutrient, means more Veggies

[Jonathan Kadish NYC AA Chair]

I have been running at 1 fish per 10 gallons in a 26 gallon tank (two 5 inch goldfish) and 4 cubic foot grow bed. I have grown basil, tomato, bok choi, lettuce, peppers ect for the last year and a half years. 9 pounds of fish is overkill for a media system unless you have a grow bed 5-10 times the volume of your tank.

Those high stocking ratios are for DWC systems with solids filtration. The real way to think of it is how much fish food does my system need to grow plants and you will find that 15-25 grams per square meter per day of grow bed is more than enough. DWC has a much higher number of 60-100 grams.

You will also find that dealing with your water chemistry is a lot easier with lower feed rates.

[Harold Sukhbir]

Hi Jonathan,

You're right. My mistake Ariel,sorry. Rules of thumb for media bed is 1 lb of fish for 5-7 gallons, so that makes 5-7 one pound fish.

[Vlad Jovanovic]

Folks, is it just me, or are we sometimes talking "apples and oranges" or "grandmothers and frogs" as they like to say around here...

When addressing stocking densities there are two 'rules of thumb'...each address a different aspect of ratio:

1) For the bio-filter...1lb of grow out fish per cubic foot of media (that is the generally accepted MAXIMUM bio-mass that that amount of FILTRATION will support...it doesn't seem to take even near that number of fish to grow some plants well...and it has nothing to do with how big your fish tank is)...

2) For the fish tank...1lb of fish per 5-7 gallons of fish tank water (anything more dense and crowding, oxygen, blablabla...becomes an issue)...

Remember, stocking density should be based on system bio-filtration capacity rather than fish tank size...i.e if you have a 1000 gallon fish tank it would be pretty catastrophic to stock 1lb of fish per every 7 gallons...if you only have say...one 4' x 4' x 12" deep media bed for filtration...

I'm with Jonathan...It seems like we have gotten away from some very basic operating principles... an AP system like any food (or otherwise) production system is an INPUT/OUTPUT system at heart. There is no getting around it. I've said it a hundred times, and I'll say it a thousand more...The fish feed is your main input and EVERYTHING should be based around the quality of (composition, protein content etc...), and the amount of fish feed (input) going into the system. It is both your fish food and your plant food... This seems to be at the heart of (as it should be) all the 'old time' AP research and literature. Somewhere along the line of 'popularizing' AP certain very basic ideas/operating principles seem to have gotten 'dumbed down', lost, glossed over, misrepresented, or forgotten. 

Look to Rackocy, Lennard, Leonard, Savidov... their literature, tools, calculators for an understanding of where these ratios come from...

[Ariel Scott]

Thanks for the replies everyone.  I think based on all this info I am going to stock about 5-6 goldfish for now.  I have about 40 gallons of grow bed fully stocked with plants so I think the bio-filter should be able to handle it. 

[Verna Gross]

Ariel. When I first started my system which is a 250 gal tote we did fish less cycling, we started with 6 3-4 inch goldfish no one died then we got 35 1-2 inch Tilapia fingerlings in Feb and added them everyone is thriving and growing including my plants we have about 40 sq ft of grow beds my ammonia stays around .25 nitrites 0 pH 6.4-6.8 nitrates 80+

[Harold Sukhbir]

Hi Ariel,

From the discussion so far I see you did your homework before setting up your AP. With a 35 gal FT and a 40 gal GB, you're close to a 1:1 ratio. As for your initial concern;

" When I test for Nitrates its usually around 0 so I'm wondering if I need to add more fish or if the nitrates will increase as the fish grow."

In startup AP, and outside the rules of thumb, we may tend to have high plant stocking densities, or we may stock fruiting plants or plants which require lots of nutrient for growing as compared to less demanding plants like leafy greens. In such a case plant growth may be slower than normal and the system takes a longer time to build Nitrates.

Even when we plant with low densities, with leafy greens etc., because the fish are small and feeding rates low, it still takes a long time for the AP to gather its full potential. So to answer your question, yes you can add more fish or you can wait for them to grow. Its a choice for the operator!

My approach, based on the fact that I live in the tropics with high temps and plentiful sun, is to increase the fish load. I've stocked in most systems up to 4 times the 1 lb ratio for fish, having to cull fish every couple of months to maintain the nitrogen load on the system. What are the advantages of doing this? I mostly view AP from the vegetable production output, and i plant fruiting plants during system startup. At 3 months of a system startup, I usually harvest ripe tomatoes, peppers, and bitter melon. I try to maximize the AP and take full advantage of the growing conditions.

One had to be more prudent though with systems in temperate countries, as you should, as light and temperatures are both limiting factors in AP.

[Ariel Scott]

Thanks Harold, that is helpful information.  Currently I mostly have leafy greens such as lettuce and kale which are growing however, not as fast as when I was adding the liquid ammonia because the nitrates were much higher. 

Maybe an option would be to add more fish then the recommended stocking density and when they grow larger find a new home for a few of them.  I just didn't want to add too many fish at once and overload the bio-filter.  I think a good option is to add a fish or 2 at a time, wait a week and see how the system handles it.

Harold Sukhbir said:

Hi Ariel,

From the discussion so far I see you did your homework before setting up your AP. With a 35 gal FT and a 40 gal GB, you're close to a 1:1 ratio. As for your initial concern;

" When I test for Nitrates its usually around 0 so I'm wondering if I need to add more fish or if the nitrates will increase as the fish grow."

In startup AP, and outside the rules of thumb, we may tend to have high plant stocking densities, or we may stock fruiting plants or plants which require lots of nutrient for growing as compared to less demanding plants like leafy greens. In such a case plant growth may be slower than normal and the system takes a longer time to build Nitrates.

Even when we plant with low densities, with leafy greens etc., because the fish are small and feeding rates low, it still takes a long time for the AP to gather its full potential. So to answer your question, yes you can add more fish or you can wait for them to grow. Its a choice for the operator!

My approach, based on the fact that I live in the tropics with high temps and plentiful sun, is to increase the fish load. I've stocked in most systems up to 4 times the 1 lb ratio for fish, having to cull fish every couple of months to maintain the nitrogen load on the system. What are the advantages of doing this? I mostly view AP from the vegetable production output, and i plant fruiting plants during system startup. At 3 months of a system startup, I usually harvest ripe tomatoes, peppers, and bitter melon. I try to maximize the AP and take full advantage of the growing conditions.

One had to be more prudent though with systems in temperate countries, as you should, as light and temperatures are both limiting factors in AP.

[Harold Sukhbir]

Hi Arial,

There are many options available to system design in AP, it really depends on the aims/goals of the operator. As long as we understand the basics of AP we can design AP to suit our individual needs. While goldfish are ornamentals, and are not for the dinner plate, I'm sure a pet-shop would be more than willing to accommodate them when the time comes, should you decide to increase your fish load.

Remember if you don't over feed the bio-filter your readings will remain balanced, so even with higher than the ratios numbers of fish you can control your total system nitrogen. Fish are unique animals, just observe them in the wild, they grow in proportion to the food available to them. Just keep a close eye on your water parameters as you go along and all will be fine.