something that I made and fed to both my Rivulatus' and Midas' was as follows:
1 pound of (wild caught *only*) cod
a small garlic bulb
4 packets of Knox gelatin
crushed up flakes / pellets / any other daily food used
a bag of peas
mince/puree the garlic in a cup
crush up any pellets / flakes you normally feed
blend the cod (or any *wild caught* white fish) as fine as possible
then follow the directions on the Knox gelatin packs... adding the mixture to the water while heating the water
-I added the pureed garlic in with the gelatin
once you remove the pot of water from the burner, add all your ingredients and mix thoroughly
Once satisfied with the consistency, spread it over a cookie sheet or two - approximately 1/4" thick and place in the fridge
I let my trays sit in the fridge overnight, removed them the next morning to cut up in to sheets, stuck the sheets in Ziploc bags, and threw them in the freezer
my fish devoured the food: