Has anyone found a source of feed for their tilapia that doesn't have fish meal in it? I"m not having any luck finding anything I consider sustainable so far, and I'm too busy / lazy right now to start up a duckweed system. Thoughts?
I have not started my own aquaponics systems, but I plan on doing just that quite soon. I am still in the progress of getting all the expensive parts together.
As far as cheap fish food, here are two ideas I have come across. 1) Put a bug zapper above your fish tank. Bugs fly to trap. Bugs get zapped. Fish are happy. My co-worked used this for his catfish and they loved it.
2) Raise soldier fly larva. I have not tried this, but the idea is simple. Throw left over food into a bucket with some sort of ramp in it. You can cover the bucket, but drill holes in the bucket so that the eggs can be laid in the food. Let it sit. The complicated part seems to be getting the larva out. I saw one guy who was manufacturing a system that gave the larva a little ramp to climb up. It looked to me like their natural instinct was to go up, so they just kept trying to climb up that ramp over and over again until he scooped them up and fed them to his fish.
3) I lied, I have heard of a third idea. Throw your leftover food scraps into your fish tank. I know somebody who did this while raising tilapia. I am guessing you would want to stay away from really oily food, meats, and dairy products.
Love all your ideas, David! Can't do soldier fly here...too dry in Colorado, but I want to try the other two. Just found out yesterday that at Growing Power they feed the tilapia scraps from the salad greens harvest during the week, and only resort to commercial fish feed on the weekend.
So, what are all the components of Tilapia or Trout feed? Is there some easier, more local/sustainable way to get our aquaponic fish these nutrients. Can't imagine Duckweed only would be enough or maybe it'd take 2 1/2 years to grow them to reasonable harvest size on a "diet." Where's Joel Salatin when I need him?
The problem child is the fish meal, which is the source of protein in commercial feed. Was just reading an article that came out today in the Christian Science Monitor - http://www.csmonitor.com/Environment/2010/0224/Recirculating-aquacu...(page)/2 - that outlines the problem pretty well. In the wild, fish eat fish, but because we have made such a mess of the oceans we can't be harvesting wild fish to feed our farmed fish and think we are solving the problem of overfishing the oceans. Veg based feeds are being developed and should be coming out soon, but as best as I can tell right now the choice we have as home growers is either buy commercial feed with it's problems and/or feed your fish duckweed and other home-grown sources of food. They will grow, but not as fast. Honestly I'm doing both. I mostly rely on commercial feed, but constantly throw in produce scraps as a supplement. I want to try duckweed this spring.
I've also found there is a wide variety of quality between feeds. I do rely on commercial feed since the bug zappers, worms and bsf are not really up to completely filling the diet. (as for getting a good price on high quality feed for recirculating aquaculture, I find out what company distributes the type of feed I want to buy and find out what local feed stores are dealers in that type of feed. Then I call them and see what price they will charge and if good, ask them to have a bag or two put on the next delivery truck, since most feed stores don't stock much in the way of fish feed and the "pond diet" for farm ponds is definitely not very good for recirculating aquaculture.)
Just a point, BSF and worms are often too fatty to be the sole feed for tilapia or catfish without additional processing. I've grown duckweed for the tilapia, it takes a huge amount of space to grow enough duckweed to feed even a dozen tilapia long term in warm weather. I could put 12 tilapia in a tank 16 feet long by 3 foot wide and completely cover the top with a thick layer of duckweed and if I didn't feed them anything else, the duckweed would all be gone in a week to ten days.
I've thought about trying to mix up my own feed but don't have the money to invest in a pellet mill at this point in time.
Duckweed could be a pretty good source of food for larger (read don't need really high protein feed anymore size) tilapia but it takes a fairly large area or a well designed system to grow enough of it to really make a dent in the feed bill.
I've been using AquaMax Dense Culture Feed 4000 (it is a Purina product) They do have other products as well for different types of fish and such. The Dense 4000 is I think 36% protein and appropriate for growing out Tilapia and Catfish in recirculating aquaculture. I just go to the Purina web site and look for Purina dealerships in my area and phone them up to see if they can get me the product and for how much, then if I like the price I'll ask them to put a bag or two on their next order. (Now this works with most feed stores, however, Tractor supply is now a Purina dealer but they will only stock certain products and you can't special order through them since they have a central warehousing system and the deliveries to the stores come from the central warehouse and not from Purina directly.)
I would like to be more sustainable about the feed and an even bigger point is the health aspect. Sadly not only do the commercial feeds use fishmeal, they use lots of corn and soy since those are cheap. Well, corn and soy have not such good ratios of the Omega fatty acids. (we want high Omega 3 and lower Omega 6 and 9) Corn and Soy have rather high amounts of Omega 6 and no where near enough Omega 3. Well we are what we eat and so are our fish. I did some research on the Omega content of farm raised catfish and tilapia compared to wild caught, the wild caught catfish at least are far healthier to eat based on the Omega ratios. However, trying to mimic a wild diet for a catfish in a tank is quiet a challenge, so I'm still feeding mostly pellets and occasional worms/BSF and Zapped bugs. I figure at least I know my fish haven't been in polluted waters or fed medications at a farm.
Perhaps you can adjust you water flow and aeration such that it would help keep the food from floating into the plants before the fish have a chance to eat it. That might be kinda tricky to balance and keep the plants from floating to the spot you are trying to keep the food.