Chen's lizard loach

Formosania chenyiyui

Also known as Chen's hillstream loach, Mallard hillstream loach

FreshwaterFish

Chen's lizard loach (Formosania chenyiyui) — The Wet Spot Tropical Fish · Used with permission

Care at a glance

Temperature: 61–75°F (16–24°C)
pH: 6.5–7.5
Adult size: 3.6 in (9.2 cm)
Minimum tank: 25 gal (95 L)
Temperament: Mostly peaceful
Social behavior: Social
Swim level: Bottom
Difficulty: Difficult
Breeding: No record
Rarity: Rare
Origin: Zhejiang and Fujian, southeastern China
Family: Gastromyzontidae

Overview

Chen's lizard loach is a slim, active bottom dweller that ranges over stone more than it perches, so give it a long, open floor and keep it in a small group of five or six. It is mostly peaceful and pays little attention to tankmates, though males will nudge one another off prime grazing spots. Most of its diet is the biofilm and algae it scrapes from rock, so mature the tank first, then supplement with fine sinking foods, crushed wafers, and small frozen items. Suitable companions are calm, cool-water fish that can hold their own in current without bullying it. A tank of around 95 liters or more, wider than it is tall, gives it the running room it wants.

In the wild

This loach lives in cool, coastal-range streams of Zhejiang and Fujian in southeastern China, where rain and runoff keep the water cold and fast for much of the year. It needs genuinely cool conditions, 16 to 24 C, so summer heat is the main risk and a fan or chiller may be needed in warm rooms. Give it torrent-grade flow, high oxygen, smooth grazing stones, and a pH of 6.5 to 7.5.

Good to know

Formosania is a group of elongate hillstream loaches in the family Gastromyzontidae, and this species reaches about 9 centimeters. The genus name is a replacement coined by Oshima in 1919 for an older name that was already taken, and it refers to Formosa, the historical name for Taiwan. The fish itself is named for a Chinese ichthyologist called Chen. Its reproduction has not been recorded in aquaria.

Did you know

The genus name exists only because of a naming clash: the loaches were first placed in Crossostoma, but that name already belonged to a fossil snail, so Formosania was coined in 1919 to take its place.

Tank mates

Chen's lizard loach is a mostly peaceful, social species that keeps to the bottom. These picks match on water type, temperature, pH, size and temperament.