Corydoras and armored catfish

Corys shoal, and six of one species is the minimum. They will mix with other corys but school by species, so six of one beats two of three. They feed by pushing their faces into the substrate, so fine sand or smooth rounded gravel keeps the barbels intact where sharp gravel and a dirty substrate wear them away. Feed sinking pellets or wafers and frozen food after the lights go down, when the mid-water fish are not competing, because a cory eats what reaches the floor and is not a cleanup crew. Then read the temperature on the profile before you buy, because several of the popular corys are cool-water fish and an 80°F (27°C) community shortens their lives.

1. 01

   Six or more

   One species per group, six of one beats two of three

2. 02

   Sand or smooth gravel

   Sharp gravel and a dirty substrate wear the barbels

3. 03

   Sinking food after dark

   Pellets, wafers and frozen food, not leftovers

4. 04

   Check the temperature

   Several popular corys are cool-water fish

The blue cory and the gold laser cory list 68–73°F (20–23°C), the banded cory 66–75°F (19–24°C), Ehrhardt's cory 66–77°F (19–25°C) and the dirty bandit cory 70–75°F (21–24°C). The sailfin cory lists 64–70°F (18–21°C) and belongs in an unheated tank. Even the panda cory tops out at 77°F (25°C). None of them is a fish for a discus tank. Warm-water corys such as Sterba's cory, the mosaic cory, the pretty cory and Amanda Jane's cory list up to 82°F (28°C). They fit a discus tank only at 79–82°F (26–28°C). The serratus cory goes to 84°F (29°C) but is marked difficult. The strip above shows the band most of the family shares, 72–79°F (22–26°C), so a community set in the mid 70s suits the majority.

The pygmy cory stays at 1.3 inches (3.3 cm) and lists 10 gallons (38 liters). The dwarf cory is the same size on the same minimum. The nano cory, the salt and pepper cory, Reynolds's cory, the barred-tail cory and the sixray cory stop at 1.4 inches (3.5 cm). Unlike the larger corys, the pygmy and dwarf corys spend much of the day hovering in mid-water in a tight shoal, which makes them look like a school of tiny tetras with whiskers. Keep them in tens rather than sixes, with fine food such as crushed pellets and baby brine shrimp, and away from anything that could swallow them. A 10 gallon (38 liter) tank with sand and floating plants suits a group of pygmies.

In 2024 the genus Corydoras was split into several genera, and the catalog uses the new names on each profile. The bronze cory is now Osteogaster aenea, the panda cory Hoplisoma panda, the pygmy cory Gastrodermus pygmaeus and the emerald catfish is back in Brochis; only the long-snouted species such as Fowler's cory stay in Corydoras. The Aspidoras corys, such as the albater cory, have always had a genus of their own. The banded cory was Corydoras barbatus until Scleromystax was revived in 2003. The common names, the care and the fish are unchanged, and the shop label will say Corydoras for years yet. Search by common name and most profiles show both.

The rest of the family are the hoplos, the porthole catfish and the cascarudo, bigger fish with the same armor. The hoplo catfish reaches 7.9 inches (20 cm), lists 40 gallons (150 liters), is marked easy and builds a bubble nest at the surface. It eats small invertebrates, so dwarf shrimp are not safe with it. The spotted hoplo is a peaceful 5.9 inch (15 cm) fish that takes 64–82°F (18–28°C). The bar-tailed hoplo is boisterous at feeding time and wants robust tankmates of a similar size. The dwarf hoplo stays at 2.6 inches (6.5 cm) and prefers cooler water, 68–75°F (20–24°C). The porthole catfish and the flagtail catfish are peaceful bottom foragers at 3.9 to 4.9 inches (10 to 12.5 cm). Both do best in a group of four or more, and the flagtail often rises into open water. The cascarudo and the hoplo catfish tie as the biggest fish on this page at 7.9 inches (20 cm). The cascarudo lists the largest tank, a 63 gallon (240 liter) minimum. It may eat very small fish and shrimp.