PERCHES
NANDIDAE FAMILY
The Nandidae, or Leaf Fish family, consists of generally small fish characterized by a small head and a large mouth. Several species are considered "oddities" in the aquarium hobby due to their leaf-like appearance. By using this natural camouflage, Leaf Fish can hunt with little detection from their prey. Nandus species are found in South America, Southeast Asia, and Africa.
South American Leaf Fish, Barbeled Leaf Fish
Monocirrhus polyacanthus
SYN: Monocirrhus mimophyllus
Physical Description (PD):
An oval-shaped fish with strong lateral compression. It has a large mouth with an extended lower jaw. The anal and dorsal fins have long bases composed of small spines.
Its coloration is highly adaptable to match its surroundings, typically ranging from orange-yellow to brown with various dark markings that give it the appearance of a dead leaf.
Three dark lines accentuate this mimicry:
- One extends from the eye to the belly
- Another runs from the mouth, through the eye, to the caudal fin
- A third runs from the eye to the first dorsal fin rays
Size (SIZE): Up to 4 inches (10 cm)
Similar Species (SS): Other Leaf Fish species.
Habitat (HAB):
Inhabits shallow, vegetated shorelines of slow-moving or still waters in South America, particularly in the Rio Negro and Guyana.
Swimming Level (S): Primarily middle to bottom.
Tank Requirements (TANK):
- A tank measuring 28 inches (71 cm) with a volume of 20-25 gallons (76-95 L) is adequate.
- The aquarium should be densely planted, particularly with large-leafed plants.
- Floating plants should be used to diffuse light and provide cover.
- Dark-colored substrate and decorations enhance the fish's natural camouflage.
Water Conditions (WATER):
- pH: 5.0 - 6.8 (optimal ~6.5)
- Hardness: 2-10 dH (ideal ~6 dH)
- Temperature: 73-84°F (23-29°C)
Behavior and Compatibility (SB):
- A solitary predator that should not be housed with smaller fish.
- If combined with other species, select larger, robust fish that it cannot prey upon.
Compatible Tank Mates (SC):
- Preferably none, as it will consume smaller fish.
- If necessary, suitable tank mates include Armored Catfish, Pictus Catfish, and robust mid-to-large species such as Leporinus, Anostomus, and Myleus.
Diet (FOOD):
Carnivorous, requiring live prey such as:
- Small fish
- Mosquito larvae
- Earthworms
- Aquatic insects
- Tubifex worms
- Crustaceans
It may refuse dried or frozen foods, making a steady supply of live food essential.
Sexing (SEX):
Females appear rounder during the spawning season.
Breeding (B):
- A breeding tank should house a single pair.
- Ideal water conditions:
- pH: 6.0 - 6.5
- Hardness: 2-4 dH
- Temperature: 77-82°F (25-28°C)
- The male cares for the eggs (~300), which are attached to the underside of large-leafed plants.
- The female should be removed after spawning, as the male may become aggressive toward her.
- The fry hatch in 60-90 hours and must be fed small moving foods such as Brine Shrimp nauplii.
- The young grow at different rates and must be periodically sorted by size to prevent cannibalism.
Breeding Difficulty (BP): 8 – Breeding is challenging.
Remarks (R):
- The South American Leaf Fish stalks prey by mimicking a floating leaf, often orienting its head downward for disguise.
- It approaches its prey using transparent pectoral fins, making it nearly invisible.
- When striking, it rapidly expands its mouth, creating a vacuum effect that sucks in prey instantly.
- This species has color-changing abilities, allowing it to blend into its surroundings.
- Avoid sudden disturbances in the aquarium, as this species is easily startled.
Difficulty Level (DC): 7 – Requires stable water conditions and a live food diet.
Nandus
Nandus nandus
SYN: Bedula hamiltonii, Coius nandus, Nandus marmoratus
Physical Description (PD):
An oval-shaped fish with an arched back and laterally compressed body. The first 12 rays of the dorsal fin are spiny, while the remaining rays are soft. The caudal fin is fan-shaped, and the mouth is deeply cleft, well adapted for ambush predation.
Body coloration varies but is generally gray with irregular brown markings. The eyes have two distinctive brown stripes:
- One runs from the mouth to the origin of the dorsal fin
- The other runs from the throat through the eye
The fins are grayish with brown markings.
Size (SIZE): Up to 8 inches (20 cm)
Similar Species (SS): Other Leaf Fish species.
Habitat (HAB):
Found in swamps, coastal lakes, and rivers in Southeast Asia, particularly in Burma (Myanmar), Thailand, and India.
Swimming Level (S): Bottom, middle.
Tank Requirements (TANK):
- A 36-inch (91 cm), 35-45 gallon (132-170 L) tank is recommended.
- Should be densely planted, with a cover of floating plants to mimic its natural habitat.
- Use rocks, roots, and wood to create hiding places.
Water Conditions (WATER):
- pH: 6.9 - 8.0 (optimal ~7.4)
- Hardness: 8-15 dH (ideal ~12 dH)
- Temperature: 73-81°F (23-27°C)
- A 0.5-1.0% salt addition is beneficial (~5-10 g per 10 L).
Behavior and Compatibility (SB):
- A nocturnal, predatory species that will prey on smaller fish at night.
- Best suited for a species tank but can be housed with large, robust tank mates.
Compatible Tank Mates (SC):
- Large species only, such as Giant Gourami, Mystus Catfish, Knifefish, and large barbs.
Diet (FOOD):
Carnivorous, requiring live prey:
- Small fish
- Insects
- Insect larvae
- Crustaceans
- Worms
Sexing (SEX):
Difficult to distinguish; males may be darker with larger fins.
Breeding (B):
- Breeding is rare in captivity.
- Requires a pH of 6.8-7.0, hardness of 6-9 dH, and temperature of 77-81°F (25-27°C).
- Spawns up to 300 tiny eggs, which hatch after two days.
- Parents do not guard the eggs, so they should be removed.
- Fry can be raised on Artemia nauplii.
Breeding Difficulty (BP): 9 – Rarely accomplished in captivity.
Remarks (R):
- This species is nocturnal.
- Prefers a low-light, heavily structured habitat.
- Requires live food for survival.
Difficulty Level (DC): 7 – Predatory and sensitive to water conditions.
Schomburgk's Leaf Fish
Polycentrus schomburgki
SYN: Polycentrus tricolor
Physical Description (PD):
A stocky, high-backed fish with lateral compression.
The body is oval-shaped, and the caudal fin is fan-shaped.
Both the anal and dorsal fins have long bases with short, spiny rays.
Coloration is highly variable, depending on mood and environment, but generally dark brown with scattered light and dark markings.
Three dark lines run from the eye to different points on the body.
The fins are brownish.
Size (SIZE): Up to 4 inches (10 cm)
Similar Species (SS): Other Leaf Fish species.
Habitat (HAB):
Inhabits slow-moving, vegetated waters in South America, specifically in Trinidad, Guyana, and Venezuela.
Swimming Level (S): Bottom, middle.
Tank Requirements (TANK):
- A 20-inch (51 cm), 10-gallon (39 L) tank is sufficient.
- Prefers low-light conditions with a dark substrate.
- A cover of floating plants is essential for this species.
Water Conditions (WATER):
- pH: 6.3 - 7.2 (optimal ~7.0)
- Hardness: 8-20 dH (ideal ~10 dH)
- Temperature: 72-79°F (22-26°C)
Behavior and Compatibility (SB):
- A solitary species that is peaceful toward similarly sized fish.
- However, it is predatory toward smaller fish.
- Nocturnal; prefers dimly lit environments.
Compatible Tank Mates (SC):
- Armored Catfish, Leporinus, Anostomus, Angelfish, Doradids, Loricarids, Loaches.
Diet (FOOD):
Requires live prey:
- Small fish
- Mosquito larvae
- Earthworms
- Aquatic insects
- Crustaceans
- Tubifex worms
Sexing (SEX):
- Females are rounder during spawning and generally lighter in color.
Breeding (B):
- Requires pH 6.0-7.0, hardness 18-20 dH, and temperature 82-86°F (28-30°C).
- Spawns in a rocky cave, attaching ~600 eggs to the underside of large-leafed plants.
- The male guards the eggs and chases away the female after spawning.
- The fry hatch in 3 days and become free-swimming after 7-8 days.
- Fry grow rapidly and must be separated to prevent cannibalism.
Breeding Difficulty (BP): 8 – Difficult.
Remarks (R):
- Less aggressive than M. polyacanthus.
- Prefers low-light, heavily structured environments.
Difficulty Level (DC): 6 – Requires live foods but is less aggressive.