Three-lined Cory

The three-lined cory is one of the most commonly sold spotted corydoras in Europe and Türkiye; however, it is often mislabeled as "julii". Its pale gray body has wavy, maze-like black lines on the head and back, and a thick, unbroken black stripe running along the lateral line on the sides. The tip of the dorsal fin is black, and the tail is spotted in rows.

The difference from the true C. julii is easiest to see on the head: the julii's head is covered with separate round spots and its side stripe is thin, faint and short; in trilineatus the head pattern consists of wavy lines that join up with each other. In terms of care there is no difference between the two species.

A large share of the fish sold today are captive-bred and adapt easily to a wide range of water parameters.

It is distributed over a wide area of the upper Amazon basin in Peru, Colombia, Ecuador and Brazil. It lives along riverbanks, in still backwaters and floodplain lakes, over sandy or leaf-littered bottoms. These varied habitats explain the species' hardiness in the aquarium.

• Volume: at least 60 liters for a group of 6–10; footprint matters more than volume.
• Substrate: fine, rounded sand. If gravel is used, it should be very fine with rounded edges.
• Water: 22–26°C; pH 6–7.5, soft to moderately hard. Keep nitrate low with regular water changes (25–30% weekly).
• Decor: shaded resting areas with roots and plants; open sand at the front.

Make sinking tablets and granules its staple food. Frozen bloodworms, brine shrimp and daphnia can be given several times a week. Sinking food given in the evening reduces competition with fast midwater fish.

Calm and peaceful; it does not bother any fish or shrimp. In groups the fish forage on the bottom and now and then dart to the surface to gulp air.

Good companions: almost all peaceful community fish: tetras, rasboras, platies and guppies, gouramis, angelfish, dwarf cichlids, shrimp.

Avoid: aggressive cichlids that claim the bottom, large predatory fish.

At least 6, ideally 10 or more individuals. In the wild it lives in large schools; in the aquarium, too, a large group is more active and visible. It can roam together with julii and other similarly patterned corydoras.

It is easy to breed in the aquarium. A large, rather cool water change often triggers spawning. After taking up the "T position" with the male, the female sticks the eggs to the glass, the undersides of leaves and the filter sponge. The eggs hatch in 3–5 days; since adults may eat the eggs, they can be moved to a separate container.

• Barbel erosion: sharp substrate or dirty sand.
• Red gills, rapid breathing: may be an ammonia or nitrite problem.
• It is sensitive to salt and copper-based medications.

Viewed from above, females are broader and plumper; males are slimmer and slightly smaller, with more pointed pelvic fins.