Essentially, underwater compost. Consists of vegetative matter and animal manure such as rabbit pellets or chicken droppings.
Microbes and protozoa live there, and turn the mass into a gluey (gleal) mass of lifeforms.
Tilapia will eat this mass, and it is reported that this could provide 100% fish food.
Suggestion on brewing zoogleal mass in buckets - try to brew some slop/mass out of the ponds for the first run and then dollop it in when it is gelatinous to see what the tilapia do. If they love it, then try submerged in the ponds.
The following is supposed to be an embed code for a FB post on zoogleal mass, but it does not show the actual pictures.
Zoogleal Mass 101. We use compost tea and fish water to feed the aquaponic plant towers. But how to feed the fish? Now we use fish food, and duckweed/azolla will add significantly once it really gets going. But the most promise for self-funding of fish with plants as the only input is zoogleal mass - underwater compost. Our initial experiment- hay in a 5 gallon bucket, submerged in water from the fish pond. This should start growing microbes and protists etc - a gluey (gleal) mass of digested grass. This zoogleal mass would be fed to our tilapia fish, and our goal is to replace any commercial fish food and thus feed the fish 100% on local grass. Our design requirement for the aquaponic greenhouse is that sunlight and grass are the only inputs once the ecosystem is running.