Backyard Aquaponics
A place to discuss aquaponics

my first system is fully cycled and i have about 12 goldfish and 3 picastomus,( black algae eaters) and i am not sure if i should add more.
the fish are in a 37 gal tank and there are 2 18 gal sumptanks.
how do you know how much fish can be supported by the system. all important levels are reading 0. the goldies range from 2" to 1", they are just feeders from the pet store. i know it can handle more fish, but i dont want to get to many and have them suffer, or have too little and have the plants suffer.
any ideas?
thanks

What is your nitrate level?
Are your plants showing signs of nitrogen deficiency?

If your nitrate is 0 and your plants are having their LOWER leaves turn yellow and die off then maybe you need more fish or a higher quality fish feed. Remember that aquarium fish feeds are often developed to provide the least amount of nutrients while keeping the fish alive (since more nutrients means the aquarium keepers have to do more water changes) while in aquaponics we want those nutrients to feed our plants so a fish feed designed to grow fish out will provide more food for our plants as well.

i am using high protein shrimp pellets, and the nitrates level is at zero. i havent noticed any signs of deficiency in the plants that i can tell, but i am so new that i am not sure i would notice any major problems until they were major.
that being said there are no individual leaves that are looking different from other leave on the same plant. several plants look paler then i would like, but that might just be the variety because other plants look great. i added a spoon of chelated iron several days ago, and again 2 weeks before that, attempting to darken the green of the leaves. so i will add a few more fish.

Just out of curiosity, do you keep goldfish purely for the nutrients?

I just wonder why people keep goldfish versus some other food fish (I suppose you can eat goldfish) or anything else? They're pretty good nitrate generators but it seems to me you might be better off with a pure hydroponics setup if you don't care about the fish portion of the setup. Or Tilapia since they're pretty easy and you can always give them to friends to eat.

Unless it's just for the fun/experience of starting out. I've seen a few other forums where people use goldfish and I haven't seen any 'practical' reasons yet.

There is a number of reasons people use goldfish.

*Cost
*Availability
*Sturdiness
*They are not cannibals
*Unfamiliar with other species
*Easy

Just to name a few.

Just because someone uses goldfish doesnt mean they dont want to grow edible fish, they may just be trying things out till they are comfortable to bring in other species. A lot of people just use them to cycle systems. The most important thing to remember is that the difference between AP and Hydroponics is the use of chemicals. I would prefer to use goldfish than chemicals any day, home grown, all natural vegetables.

Sorry to be blunt but I think you missed why most people do aquaponics.

p.s. Goldfish dont generate nitrates. No fish do for that matter. You may need to do some reading.

I mentioned that. I don't think my question implied people who grow goldfish don't eat fish, it was just a 'theory' as why -I- thought might be one of the reasons. The root of the question was trying to get the full story because I do see a lot of people using it.

Basically, in case I'm not clear, I wanted to know whether I wasn't being imaginative enough or there was some fact I was missing.



I don't think that's being blunt. There's a good chance I did miss the motivation of why most people go into aquaponics. With that said, I do feel that you either don't understand my question or are drawing incorrect conclusions about my motivation for posting the question.

I asked the question not because I'm looking down on goldfish, but because I genuinely wanted to know if there was something that I didn't know about goldfish for aquaponics. From the reading I have done, most people's motivation is for sustainability, cost-efficiency, and fun. From what I had read, it seemed a lot of people use goldfish and it didn't make sense (in my mind) versus other species. Hence, the request for clarification...

So if in some way, you or someone felt I was being condescending towards goldfish or people who kept goldfish, I apologize.

With that said, I do know (or at least recognize) that people do it for other reasons like not wanting to use artificial fertilizers.

Summary: In the interest of trying to balance clarity and not sounding like a broken recorrd, I was trying to resolve what I know, what I've read, what I understood, to what I have seen.

So thanks for the info/perspective.



Fair enough, I made a false statement regarding nitrates, so I'll clear up any doubt about my level of (mis)understanding. I know nitrates don't come directly from fish. Just like cheese doesn't come from cows or any kind of mammal.

Here, here! I could only afford 20 Tilapia ($2 per), so I supplemented w/ goldfish at $.13 each. We'll get there, you rich people

LOL, I guess I did kind of lose perspective too... Coming from the aquarium end of things, I do think of fish at a smaller scale/quantity.

Are you planning on eventually breeding your tilapia? Do most people have a separate tank to breed their fish? I imagine it's not that easy to breed in a community tank unless you have a very massive setup.

Again, just curious so don't 'blunt' me to death

This was your statement , I didnt take it as condescending nor did I think you were implying anything. I was basically helping you understand "the practical reasons" why people use goldfish.



This statement led me to believe you didnt understand why people do aquaponics. Sorry for the misunderstanding...

Do you mean plecostomus?
I have never heard of picastomus.

Andrew

yes i meant plecostomus, i was shooting at the spelling cause that was how the lady at the store said it.
and to sendthis, the reason i use goldfish is because 1, i am really new and have a small system and 2, goldfish are cheap and seem to be rather hard to kill.

yer i sometimes use them as a treat for some of my bigger aquarium fish i get a bunch and i just leave them in a bucket out side

i personally dont like golfish in ponds as they are bad for the native frogs around hear but i can see them as quite usefull in an ap