Bottom-dwelling aquarium fish

For a peaceful community from 15 to 30 gallons (55 to 110 liters), the safe choices are a shoal of corydoras, a group of kuhli loaches and a single bristlenose pleco. The panda cory is 2 inches (5 cm) for 15 gallons (55 liters) and the bronze cory 3 inches (7.5 cm) for 20 gallons (75 liters), both marked easy. Sterba's cory is the cory for a warm tank at 75–82°F (24–28°C), and the peppered cory the one for a cool tank at 72–79°F (22–26°C), 2.8 inches (7 cm) for 21 gallons (80 liters). All of them want six or more of their own kind. Kuhli loaches hide by day and thread through the tank at night; keep at least five. A bristlenose pleco grazes algae, stays around 5 inches (12.5 cm) and needs a piece of driftwood to rasp. Otocinclus are the small algae eaters for a planted tank, but only once the tank is mature enough to grow the biofilm they live on.

A bottom dweller eats what reaches the floor, but it makes as much waste as any other fish and it cannot live on leftovers. Feed sinking wafers or pellets and the occasional frozen food after the lights go down, when the mid-water fish are not competing. Plecos need vegetable matter and wood; otocinclus need algae and biofilm; corydoras need a protein-rich sinking food, not flake dust. If the substrate looks clean, that is the filter and your water changes at work, not the fish.

Corydoras and many loaches feed by pushing their faces into the substrate. Sharp gravel and a dirty substrate wear down the barbels they rely on to find food and open the way to infection. Fine sand or rounded gravel keeps them intact and lets the sand-sifters do what they are built for. Give burrowers a few inches of depth and every bottom dweller somewhere to hide: caves, wood, pipes or dense plant cover.

Some of the most common bottom dwellers are sold at a fraction of their adult size. A common pleco reaches 16 inches (40 cm) and needs 85 gallons (320 liters). A clown loach reaches 12 inches (30 cm), wants 75 gallons (285 liters) and a shoal, and lives for decades. A hoplo catfish reaches 8 inches (20 cm) and a weather loach 11 inches (28 cm), and the weather loach wants cool water most tropical tanks cannot give it. The adult size and the minimum tank size are on every profile.