L128 Blue Phantom Pleco (Hemiancistrus sp.)

Common Name

Blue Phantom Pleco, L128

Origin and Habitat

The Blue Phantom comes from the Orinoco drainage in Colombia and Venezuela. It favors rocky runs and deep margins where clear, warm water pushes around boulders and fractured bedrock. Current is moderate to strong, oxygen is high, and the bottom is a mosaic of larger gravel, cobble, and slabs with pockets of sand. These fish tuck into cracks, cling under ledges, and forage over rock faces that carry biofilm and scattered invertebrates. Water is typically soft to moderately hard and can be tinted by leaf tannins after rains.

Temperature and Water Conditions

Preferred temperature is 76 to 82 F, which is 24 to 28 C. A slightly acidic to neutral pH is common in the wild, roughly 6.0 to 7.5, with low to moderate hardness. Stable conditions are more important than chasing a single number, unless you are following a specific breeding plan. Prioritize high oxygen, strong but smooth circulation, and very clean water through mature filtration and regular water changes. A powerhead or river manifold that moves water along the rockwork helps them behave naturally.

Appearance and Size

L128 is a striking dark blue to slate fish sprinkled with pale blue to turquoise spots across the body and fins. The head is broad, the body is armored with small plates, and the mouth is an underslung rasping disc suited to life on stone. Males typically show broader heads, longer pectoral spines, and more pronounced cheek and body odontodes, especially in breeding condition. Females are a little rounder through the belly when full of eggs. Maximum length is about 15 to 18 cm, which is 6 to 7 inches.

Diet in the Wild

An opportunistic omnivore that grazes rock film and picks at small benthic invertebrates. In the Orinoco it scrapes diatoms and green film, nibbles soft plant material, and consumes insect larvae, small crustaceans, and other protein rich items among stones.

Feeding in Captivity

Offer a varied menu that covers both greens and protein. Use quality algae wafers, spirulina based pellets, and soft vegetable slices such as zucchini or cucumber for daily grazing. Rotate in meaty foods several times per week, including frozen mysis, bloodworms, chopped shrimp, clams, and high quality carnivore pellets. A few pieces of hardwood or pleco wood are useful as a constant graze surface and for behavioral enrichment. Feed after lights out if tank mates outcompete them by day, and keep portions modest so food does not rot in high flow.

Behavior and Tank Setup

Blue Phantoms are peaceful with other fish that ignore them, but males can be territorial with other loricariids when cave space is limited. Plan on one adult male per tank or provide multiple caves and line of sight breaks if housing more than one male. A tank with a long footprint in the 40 to 75 gallon range suits an adult well. Build a rocky layout with piles of rounded stones and stacked slate that creates crevices, ledges, and shaded overhangs. Add several snug caves of different diameters so each fish can choose a favorite. Keep flow strong across the rock faces and through cave entrances. Tank mates should be fast midwater fish and calm bottom dwellers that will not bother a cave guarding male. Avoid nippy species that target fins.

Breeding

Conditioning: Feed a rich, clean diet with both quality greens and protein. Keep the water very clean, raise oxygen and flow, and hold temperature near the upper part of the preferred range. A series of larger cool water changes can act like seasonal rains and often stimulates courtship.

Caves and layout: Provide several tight caves oriented so flow passes across the entrance. Unglazed ceramic pleco caves, short sections of slate pipe, and carefully stacked slate all work. The opening should be just wider than the male’s head so he can block it with his body. Place caves low among rock piles. A layer of larger gravel around cave mouths helps eggs or early wigglers that tumble out find safety between stones.

Spawning: A receptive female will enter the chosen cave and deposit a clutch. The male fertilizes the eggs, then remains inside to fan and guard them. He will push intruders away and often will not leave the cave to feed while on duty.

Eggs and hatch: Eggs develop in a few days depending on temperature. Wigglers stay in the cave with the male until the yolk is nearly absorbed. If you must pull the cave, keep it submerged and stable and set it in a breeder box with gentle aeration across the entrance so the male can continue care.

Raising fry: Once the fry begin to venture out, keep food in front of them without fouling the water. Leave the male with the cave until the first fry are fully free swimming. Maintain strong oxygen and pristine water. Offer a thin sheet of high quality wafer or a small slice of blanched vegetable right at the cave mouth at lights out so the smallest fish find it first. Add finely crushed spirulina pellet, powdered grow out food, and tiny live or frozen items such as freshly hatched brine shrimp as they gain strength. Rock piles and larger gravel help because they give tiny plecos safe gaps to rest in and hold a thin film of natural food. Do not vacuum the gravel in the fry zone for the first weeks. Siphon open areas and rinse pre filter sponges often. As fry grow, increase cave options and line of sight breaks to reduce crowding, and keep a steady rhythm of small water changes.

Quick Facts

• Scientific name: Hemiancistrus sp. L128
• Common names: Blue Phantom Pleco, L128
• Origin: Orinoco River drainage in Colombia and Venezuela
• Adult size: about 15 to 18 cm, which is 6 to 7 inches
• Temperature: 76 to 82 F preferred
• Wild pH: usually slightly acidic to neutral, about 6.0 to 7.5
• Temperament: peaceful with most tank mates, territorial toward similar plecos when space is tight
• Diet: omnivore that grazes biofilm and takes protein rich foods
• Breeding type: cave spawner with male guarding eggs and fry
• Key setup: fast, clean, oxygen rich water with stone piles, snug caves, and flow across cave mouths

Tropical Fish Co. Notes

Blue Phantom is the showpiece that keeps surprising you. Under bright but gentle light the blue spots look like stars on deep water. Give them caves that feel secure, clean water that moves, and a menu that mixes greens with honest protein. For fry, think in terms of a neighborhood, not just a cave. Rock piles and larger gravel give the smallest fish safe places to start, and a thin film of natural food grows where light and flow meet stone. Keep parameters steady, keep oxygen high, and let the fish do what they have done in the Orinoco for a long time.