Hemiancistrus plecos (Hemiancistrus spp.) care guide

Group
Freshwater fish
Other names
Green phantom pleco (H. subviridis, L200), L200, Lemon spotted green pleco, Hemiancistrus medians, Hemiancistrus landoni, Hemiancistrus guahiborum
Family
Loricariidae (suckermouth armoured catfishes)
Origin
Panama to southern Brazil, mostly in South America east of the Andes (Guiana and Amazon tributaries, Orinoco, Paraná–Uruguay).
Water
freshwater
Maximum size
18 cm
Temperature
22–27°C
pH
6–7.8
Hardness
Soft to medium
Minimum tank
250 litres
Care level
intermediate
Temperament
semi_aggressive

Care

A mixed genus of plecos that PlanetCatfish lists with 17 species and Wikipedia with 12. Figures vary a lot by species, so check the species or L-number before buying. PlanetCatfish gives adult sizes from about 7 cm to 39 cm SL, with 18 cm the most common. Best known in the hobby is the green phantom pleco, H. subviridis (L200). PlanetCatfish gives it 15 cm SL, 22–25 °C and pH 6.0–7.8, and describes a home of fast-flowing water over rounded boulders and rock crevices in the upper Orinoco and Casiquiare (Venezuela). H. medians from the Maroni (Suriname and French Guiana) lives among rocks in fast, deep water and reaches 39 cm SL. Tank: for medium species like L200 we suggest at least 250 litres (an estimate). Larger species such as H. medians need far bigger tanks. Use lots of vertical stonework, rounded boulders, wood and caves, with strong current directed over the rock crevices and plenty of oxygen. Water: warm, clean, well-oxygenated water with strong filtration and regular water changes. Soft to medium hardness and pH around 6–7.5 suits most species. Identification: PlanetCatfish notes L200 is often confused with Baryancistrus demantoides, which is also green with yellow spots. Hemiancistrus has separate dorsal and adipose fins and an almost perfectly round mouth, whereas Baryancistrus has the fins joined and a more rectangular mouth. Names: Wikipedia notes the genus has long been used as a "dump" for plecos that fit nowhere else and is not a natural group. Several former species, such as H. spilomma, have been moved to Ancistomus, and many L-numbers once called "Hemiancistrus sp." are now placed elsewhere. Expect more names to change. Status: H. subviridis and H. medians are IUCN Least Concern (assessed 2020). Selling: our policies require the adult size and long-term tank needs to be stated clearly in the listing. Large fish must travel by a specialist live-animal courier (see the Livestock shipping guide). Sources: PlanetCatfish genus page (planetcatfish.com/Hemiancistrus) and H. medians (planetcatfish.com/common/species.php?speciesid=1171); Aquatic Republic, PlanetCatfish's sister database (aquaticrepublic.com/hemiancistrussubviridis); Wikipedia (en.wikipedia.org/wiki/Hemiancistrus). Checked October 2026.

Diet

Most species are omnivores. Offer algae and vegetable wafers, blanched vegetables, and meatier foods such as bloodworm, brine shrimp, mussel and good sinking pellets. L200 eats algae but still needs a varied prepared diet. Feed after dark, as they are mainly nocturnal.

Breeding

PlanetCatfish describes H. subviridis (L200) as a cave spawner. The male guards a clutch of about 40 eggs in the cave; they hatch in 3–4 days, and the fry use up their yolk sac and start feeding after 10–11 days. Give a mature pair snug caves, strong flow, warm well-oxygenated water and a rich diet. Most other species have no aquarium breeding reports (H. medians: none).

Compatibility and tank mates

Generally peaceful with other fish, but males are territorial over caves and towards other plecos, especially those of similar shape and colour. Give each one its own cave and broken-up territory. Good tankmates are fast-water community fish such as larger tetras, barbs, rainbowfish, and peaceful South American cichlids. Avoid very small or slow fish with large species, and keep only one male of each species in smaller tanks.

Last updated 5 October 2026. Community-edited care guide on Aquatic-Auctions.

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