All About Tilapia

[Miguel Afonso]

I have had many surprises whilst researching tilapia. For instance, many aquapons are reluctant to have algae in there systems, but algae comprises a large portion of tilapias natural diets in the wlld. Here is a document I have attatched well worth reading. There are a couple of things from this paper that I would like to discuss interms of aquaponics. 

1) Can you add manure (assuming pathogen free) to aquaponics system?

2) How do you introduce blue-green algae to your system, is this good?

3) Is it possible to design a system that does not require commercial feed?

 

[Harold Sukhbir]

Hi Miguel,

There are some set backs to encouraging algae growth in AP systems. Most backyard AP are done with ebb and flow and constant flood without added aeration, some are even timed flow, so managing O2 is critical for fish survival and adequate plant growth. Algae can easily rob a system, especially at night, valuable O2 and float fish by morning. Algae also consume nutrient being a plant themselves and compete for resources meant for crop growth. To a lesser extent it also competes with nitrifying bacteria for surface area reqd for growth. It also means less control by the operator on managing nutrient inputs calculated for existing crops. Algae is better cultivated in a separate system remote from the AP system, harvested and then fed to fish.

 

I'm sure that cured manure which are simply nutrient can be added to AP if the operator wishes to design an AP of this kind. Existing AP ratios have been calculated providing measured nutrient input through fish feed for growing plants.With manure these inputs become unpredictable variables and may cause too low or too high nutrient levels...from dying plants to algal blooms.

 

You can run AP on algae alone, if the operator isn't very concerned in maximizing growing of fish or yield of crop. If you manufacture SP(spirulina) as fish feed my feeling is we can get growth of plant and fish comparable to those fed on Aquaculture fish feed, although i have not seen any studies as yet on this. SP will have to be grown in its own system as they survive best in high alkaline(PH 10.3) conditions. They can grow at lower PH's but so will other types of algae as well, and thes other algae can overrun SP to the point of eliminating them altogether. 

[Michael Welber]

This is helpful because, when considering a backyard system here in Florida, I don't want to be forced to rely upon purchasing fish food regularly. Part of why I'm considering aquaponics is to become more resilient and being able to grow the fish food myself would be a large step in that direction. 

Thanks for putting this up.

 

Michael 

[Eric Warwick]

"1) Can you add manure (assuming pathogen free) to aquaponics system?

2) How do you introduce blue-green algae to your system, is this good?"

 

1. I suppose indirectly adding the nutrients to the system, such as making a aged manure tea and feeding it to duckweed and algae is possible, (I've not tried this so, I would ask someone else about it) then feeding the food to the fish thus integrating land based gardening to soil-less gardening. 

"3) Is it possible to design a system that does not require commercial feed?"

 

3. Is it possible; yes but it's most likely time intensive.

[Miguel Afonso]

3) Is it possible to design a system that does not require commercial feed?

 

I think it is possible. It just requires a 100hrs thinking and hopefully a few hours work. Nature is fully automated so it would seem that the more time we spend messing with the balance, the more counter productive we make the eventual system. The system would need to be designed based upon layering trophic levels such that the ecological efficiency( conversion of energy between trophic levels) of the system produces a surplus (what we eat) with the least input of our energy. The objective is to never expend more calories then what you extract (factor out sunlight).

With commercial feed dependance we are doing this in reverse. There are massive embedded energy costs not accounted for: transportation, production, depletion of ocean fish stocks etc. 

[Paul Holowko]

Hi Miguel,
I have an AP system where I have not feed fish for a year. They eat the algae off the walls of the tank. I made a video how to start one. Here are some responses to topics 1, 2 and 3.

1) No, do not put manure directly into the system. It will change your pH by adding anaerobic bacteria which produce acids. If you want to use poops, compost it in a worm compost until all gone, not a traditional hot and/or cold compost, extract it into the water and the nutrition will be available for the plants.
2) I use red and green algae. I start with well competed soil compost and then extract it using a 400 um bag, Both algae will appear.
3) And yes, it is possible to design a system with no feeding.

Here is a link how to do this.

http://www.gardeningrhythms.com/category/hydroponics-aquaponics/

Good luck

[Eric Warwick]

Since you mentioned trophic levels you probably know about the 10 percent rule in biology. So, I would be interested in the specifics. Are BSFL and composting worms in the mix? What about chickens--they're fairly efficient at conversion? Anyways I'd like to hear about what you've come-up with. 

Miguel Afonso said:

3) Is it possible to design a system that does not require commercial feed?

 

I think it is possible. It just requires a 100hrs thinking and hopefully a few hours work. Nature is fully automated so it would seem that the more time we spend messing with the balance, the more counter productive we make the eventual system. The system would need to be designed based upon layering trophic levels such that the ecological efficiency( conversion of energy between trophic levels) of the system produces a surplus (what we eat) with the least input of our energy. The objective is to never expend more calories then what you extract (factor out sunlight).

With commercial feed dependance we are doing this in reverse. There are massive embedded energy costs not accounted for: transportation, production, depletion of ocean fish stocks etc. 

[Paul Holowko]

Your questions bring up a lot of points that cannot be explained on a blog. What I will do is make a posting on my webpage and give all the answers to your questions..... www.gardeningrhythms.com   When that posting is complete I will let you know. Please give me a few days.
If you follow me on Twitter ... @pholowko When the page is complete, you will get a message.



[Paul Holowko]

For thoes of you who do not follow on Twitter, here is the posting I promised.

 

http://www.gardeningrhythms.com/new-tank-syndrome-break-in-cycle-st...

Eric Warwick said:

Since you mentioned trophic levels you probably know about the 10 percent rule in biology. So, I would be interested in the specifics. Are BSFL and composting worms in the mix? What about chickens--they're fairly efficient at conversion? Anyways I'd like to hear about what you've come-up with. 

Miguel Afonso said:

3) Is it possible to design a system that does not require commercial feed?

 

I think it is possible. It just requires a 100hrs thinking and hopefully a few hours work. Nature is fully automated so it would seem that the more time we spend messing with the balance, the more counter productive we make the eventual system. The system would need to be designed based upon layering trophic levels such that the ecological efficiency( conversion of energy between trophic levels) of the system produces a surplus (what we eat) with the least input of our energy. The objective is to never expend more calories then what you extract (factor out sunlight).

With commercial feed dependance we are doing this in reverse. There are massive embedded energy costs not accounted for: transportation, production, depletion of ocean fish stocks etc. 

[Miguel Afonso]

nice blog Paul.

[Paul Holowko]

Did it answer all of your questions? 

[Miguel Afonso]

I have a lot of questions....

Haven't looked at all of it yet. Did a brief scan and seems like you have tackled a great deal of interesting material. Will definately be returning when I have a little more time. 

Please feel free to post some cool topics on here, I think you have a wealth of information to share. 

[Eric Warwick]

Looks cool, but how do you maintain a healthy diet for edible fish in an ecosystem like condition? I'm not a fish expert but, I'm not sure algae is sufficient for most fish--except secondary consumers. Is there any supplemental energy added to the system when the fish have a lower growth rate. Also, would this be extremely low stocking densities. 

One more question about some language in your post,  "Take any level, the energy consumed by animals has to be absorbed by the animal or exited out the back end.  The majority of the energy is still contained in the “back end” energy waste or poop. If only 10% of the energy is consumed by the animal, 90% of it goes out the back.". Um... how I learned the 10% rule in biology was that 90% of the energy was used by each trophic level--not exited as waste. But, it's probably how I read this. Or my knowledge is a bit incomplete. Anyways that post was cool and I look forward to more.

Paul Holowko said:

For thoes of you who do not follow on Twitter, here is the posting I promised.

 

http://www.gardeningrhythms.com/new-tank-syndrome-break-in-cycle-st...