Eventually, the fish in our aquaponics systems will need to be fed. Since there is no plan to purchase fish feed, we decided it would be advantageous to investigate the Tilapia’s nutritional needs and see what can be done to formulate a feed on site. While this process is frowned upon by many ‘experts’, we feel a need to try it and see what success we can achieve. After all, fish in the wild don’t go to the store to buy groceries, why should ours?

A survey of commercial feeds yielded the following Dry Weight content guidelines:

Water                        9.0 %
Crude Protein     34.0 % (min)
Crude Fat                3.0 % (min)
Crude Fiber          10.0 % (max) (cellulose/chitin)
Ash                               8.0 %
NFE                           45.0 % (max)

Additional nutrients listed were Lysine (an essential amino acid) Calcium and Phosphorus.

My targets for a good fish feed might be in the range of the following:

Water                            8.62 %
Crude Protein         52.65 %
Crude Fat                  14.77 %
Crude Fiber                 3.20 %
Ash                                   5.33 %
NFE                                15.43 %

We expect to have various food stock available with which to formulate fish feed.
These include:

1. duckweed                 Lemna minor
2. azolla                           Azolla caroliniana
3. BSFL                             Hermeia illucens
4. red wigglers             Eisenia foetida
5. moringa tree            Moringa oleifera
6. vegetable scraps   Various

We hope to avoid purchasing additional materials but could supplement the feed if needs be.

Next week we will walk through the steps involved in generating a fish food formula based on available feed stocks. Of course, extensive tweaking is to be expected when actual fish begin to consume this formula. We will monitor intake and conversion rates as well as the general health of the fish population to be sure their complete nutritional needs are being met.