Corydoras julii are small, peaceful shoaling fish, and are typically kept in groups in captivity.

[5] Its skin is a translucent whitish-gray, with fine black spotting across the body and a horizontal stripe which reaches up the mid-body until it is equal with the front base of the dorsal fin.

Their diet consists primarily of small invertebrates which they sift from the substrate, expelling the particles of sand and sediment through their gill openings.

In captivity, their diet is frequently sinking pellets rich in insect and other invertebrate proteins, as well as live or frozen invertebrates like bloodworms, daphnia, brine shrimp, and California blackworms (Lumbriculus variegatus).

The sperm rapidly travels though the female's intestinal tract and fertilizes the eggs in the cloaca.