Blue medusa pleco

Ancistrus macrophthalmus

Also known as LDA74, Bigeye bristlenose

FreshwaterFish

Blue medusa pleco (Ancistrus macrophthalmus) — The Wet Spot Tropical Fish · Used with permission

Care at a glance

Temperature: 77–84°F (25–29°C)
pH: 5.5–7.0
Adult size: 3.5 in (9 cm)
Minimum tank: 29 gal (110 L)
Temperament: Peaceful
Social behavior: Solitary
Swim level: Bottom
Difficulty: Medium
Breeding: Medium
Rarity: Rare
Origin: Orinoco basin
Family: Loricariidae

Overview

The blue medusa is a bristlenose best kept singly or as a pair, since males claim and guard a cave and will spar with rival males. It is a night fish, hiding in wood and shadow by day and coming out in low light to graze, helped by unusually large eyes. It is peaceful with other species and fits a calm community or a soft-water South American tank. Feed it algae wafers and vegetables along with a little sinking protein, and keep driftwood and caves in the layout. A tank of about 110 liters gives a pair enough room and territory.

In the wild

The blue medusa comes from the Orinoco basin, where it shelters among driftwood and root tangles in warm, soft, flowing water. Give it a mature tank with plenty of wood, caves and shade, a sand floor and steady oxygen. Keep the water soft and acidic to neutral, roughly pH 5.5 to 7.0, and warm at about 25 to 29 C. It is shy at first and appreciates dim lighting and cover while it settles in.

Good to know

Ancistrus macrophthalmus is a stocky bristlenose in the family Loricariidae, reaching around 9 centimeters, its body slate to blue-gray and sometimes flecked with white. The name macrophthalmus means large eye, and those big eyes suit a fish active mainly in twilight and darkness. It is a cave spawner of moderate difficulty, the male tending the eggs as in other Ancistrus.

Did you know

Its oversized eyes are the clue to its habits: this is a crepuscular pleco that stays tucked away in daylight and does most of its grazing at dusk and after dark.