Platty
I am in the shop on a 3 day week wed/thurs/fri

bread and butter needed !!!!
I know that these marine based foods are there in aquaculture but there not there in the wild. the species have evolved over millions of years and here in today's world we feed food stuffs that can only be found in one place in the world !!! (spirulina) to an animal that is used to and evolved on a certain feed. Although these food stuffs make life easy for us and in some cases help with growth color and conditioning there is always a draw back ........ that we can only learn by trial and error

As for the future species that are breed on these improvised feeds it is stated that the fry, adults are although growing and coloring up better then wild found fish. They have suppressed features in the way of reproduction and immunity to genetic weakness.
Keeping it simple even though you have all the feeds ...... you are still loosing fry. Its a killer, but think back to nature if its pond scum and weed they need its just a case of finding out which one.
This i think is what the challenge is.
James.