Spiny monster pleco

Care at a glance

Overview

The spiny monster pleco is a large, thorn-armoured carnivore, the original cactus pleco, and like the rest of its genus it holds a cave and defends it against its own kind. Keep just one per tank with a big cave of its own, and choose sturdy midwater tankmates rather than other bottom dwellers it would fight. It patrols the floor by night and is otherwise peaceful toward fish it does not compete with. Feed it as a carnivore: sinking meaty foods such as prawn, mussel, and bloodworm, plus quality carnivore pellets and only occasional vegetables. Give it heavy, stable rockwork, strong flow, and a tank of around 450 liters.

In the wild

Pseudacanthicus spinosus keeps to rocky runs in tributaries of the lower Amazon, in warm, clear, flowing water. Set the tank up with large, secure stonework forming caves an adult can back into, over sand, with open channels swept by current. Keep it warm at 25 to 29 C and around pH 6.0 to 7.4, clean and well oxygenated. Firm, heavy rockwork is important, since a fish this size and strength will shift anything that is not stable.

Good to know

Pseudacanthicus spinosus is the type species of its genus, the cactus plecos of Loricariidae, named for the rows of sharp odontodes that stud the body. It reaches about 30 centimeters and carries the code L160. Its species name means spiny, and running a hand along its flank makes the reason obvious. A large carnivore, it is bred only occasionally in aquaria, so captive spawning is considered hard.

Did you know

Every row of scutes along its body carries backward-hooked thorns of hardened odontodes. Handling one with bare hands is a mistake most keepers make exactly once before reaching for a net instead.

Tank mates

Spiny monster pleco is a peaceful, solitary species that keeps to the bottom. These picks match on water type, temperature, pH, size and temperament.

• 

  Mango pleco

  Baryancistrus chrysolomus

  Freshwater

  11.8 in (30 cm)119 gal (450 L)81–88°F (27–31°C)
• Maroni eartheater

  Geophagus harreri

  Freshwater

  8.7 in (22 cm)119 gal (450 L)77–84°F (25–29°C)
• Rhino pleco

  Pterygoplichthys scrophus

  Freshwater

  12.6 in (32 cm)119 gal (450 L)77–84°F (25–29°C)
• Sharphead demonfish

  Satanoperca acuticeps

  Freshwater

  7.9 in (20 cm)119 gal (450 L)77–84°F (25–29°C)
• Bigspot eartheater

  Geophagus megasema

  Freshwater

  9.1 in (23 cm)119 gal (450 L)77–84°F (25–29°C)

• 

  Red fin thresher pleco

  Aphanotorulus emarginatus

  Freshwater

  13.4 in (34 cm)119 gal (450 L)77–84°F (25–29°C)

Check the full mix in the stocking calculator

Common questions

Related species

• 

  Red fin cactus pleco

  Pseudacanthicus pitanga

  Freshwater

  13.8 in (35 cm)119 gal (450 L)77–84°F (25–29°C)

• 

  Leopard Cactus Pleco (L114)

  Pseudacanthicus cf. leopardus

  Freshwater

  13.8 in (35 cm)106 gal (400 L)81–88°F (27–31°C)
• Scarlet Cactus Pleco (L025)

  Pseudacanthicus pirarara

  Freshwater

  15.7 in (40 cm)119 gal (450 L)79–86°F (26–30°C)

• 

  Mango pleco

  Baryancistrus chrysolomus

  Freshwater

  11.8 in (30 cm)119 gal (450 L)81–88°F (27–31°C)
• Rhino pleco

  Pterygoplichthys scrophus

  Freshwater

  12.6 in (32 cm)119 gal (450 L)77–84°F (25–29°C)

• 

  Three beacon pleco

  Leporacanthicus triactis

  Freshwater

  11 in (28 cm)106 gal (400 L)79–86°F (26–30°C)