I am keeping them in the 15 with the dario darios, shrimp, and another couple small fish. It is densely planted with mosses, low light{now},high flow, low PH, 74 degrees or so, no CO2.
They eat tiny stuff like Golden pearls in the 50-100 micron size, live grindal worms, chopped frozen bloodworms,frozen daphnia. I am sure there is microfauna they also feed on. The tank is well established-necessary. I have a paradoxus I have had over a year. These are shy fish who stay hidden and creep through the plants, occasionally swimming in the open. It's the kind of fish you are glad to see when you catch a glimpse of them.:icon_smil
My indostomus paradoxus comes out into the same clearing every day. I figure with 7 of these tiny guys, I should be able to see them more often. They are about 1/2", some less, and about as thick as a big sewing needle. Their mouth is really really small!