FishingRod,

Probably the best way to look at this problem is to ask questions surrounding the needs at various stages of development.

To start, fish are hatched with everything they need for the immediate needs of development. Interesting, but many are hatched without a mouth opening yet. They feed on their yolks as this this development takes place. As they consume their yolks, they reach a stage of development where they are able to feed on natural foods and swim a little. This stage is called swim up. At this stage they feed increasingly on natural organisms until they are free swimming (leave the nest site and free ranging). Free swimming fry fully consume their yolks and become fully dependent on consumption of foods to survive. Different fish have different behaviors and reach this stage at different sizes with different mouth sizes. How each could be fed at this stage depends to a large extent on these variables. For example, trout invest in a large egg and large yolk and their swim up are much larger than BG or LMB. At free swimming, a trout can be feed a finely granulated prepared diet. Being much larger than BG at the same stage, they consume at lower proportions of body weight. Even so, they must be feed frequently (not twice a day). When fed manually, at least once an hour, but more commonly this feeding is performed by automatic feeders that feed intermittently ... in the early going ... more frequently than that.

Free swimming BG, another story. They have small eggs and small yolks and they are a much smaller size when they reach free swimming. They feed at much higher proportions of body weight and the frequency of their feeding is much higher. They need abundant food that is dispersed throughout the water so they can encounter food that will fit in their mouth as they swim about. Abundant food organisms that are appropriately sized is critical to the survival and growth of BG fry at this stage of development. As BG grow, their consumption slows, and they can be transitioned to a prepared diet with twice daily feedings. BG production ponds, usually have enough natural foods to supply growth needs for a few weeks. They will always become food limited, but their size at reaching food limitation will depend on the number of them still surviving. As you might imagine, this can be variable. But generally, their growth is monitored and at some point before reaching food limitation, organic fertilization is curtailed and twice daily feeding is initiated. In the beginning of this, the amount is below a maximum daily feeding rate but sufficient to fuel maximum growth. They grow rapidly until the feed rate reaches a safe limit and from that point forward, they are growing slower than could be. They are growing but are growth limited.

Combinations of organic and inorganic fertilization are commonly employed so that abundant appropriately sized natural food organisms are available to BG when they reach free swimming stage. This involves filling and fertilizing a pond so that it will be in the appropriate stage of progression to provide optimum prey sizes at free swimming. Search the SRAC pamphlets for information about this.

Tilapia fall somewhat between BG and Trout in terms of size at free swimming. Like trout, they invest in a larger egg and yolk and so reach a larger size at free swimming. But unlike trout and BG, they have a much broader range of foods they can eat. When they have to be, they are detrivores, herbivores, and even carnivores. Free swimming TP will eat detritus (wasted formulated feed fits this category), plants, as well as zooplankton and phytoplankton. They are not limited to a feeding behavior of swimming about. If they are not finding enough food to grow maximally doing that, they will resort to exploiting the bottom for foods there. This combined with lower reproduction rates means it will take longer for a crop of TP to reach limitations of growth. For the production of fingerlings, organic and/or inorganic fertilization is usually sufficient and most cost effective. For grow out of the fingerlings, formulated feeds are used to maximize production.

It isn't what we don't know that gives us trouble, it's what we know that ain't so - Will Rogers