Erromyzon sp. 'ER02'

Overview

The unidentified Chinese hillstream loach Erromyzon sp. 'ER02' is traded as red spots. Pale narrow body bars and head spots contrast with a dark background, while older fish acquire red marks along the lateral line. Stable oxygenated water and abundant grazing surfaces are central to maintenance.

Distribution & habitat

It originates in southern China, although the precise range is unclear. Imports often accompany other regional loaches or gobies. Shallow, clear, fast tributaries with rocky biofilm-covered bottoms characterize the genus; they do not constitute a confirmed ER02 locality description.

Aquarium setup

A base near 60 × 30 cm is the minimum recommendation. Cover sand or gravel with smooth stones of varied sizes. Ample filtration, circulation, and aeration should maintain clean oxygenated water; suggested turnover is ten to fifteen tank volumes per hour.

Bright light supports algae. Weathered wood is acceptable, but staining from new pieces can reduce light penetration. Hardy plants and exposed sponge surfaces provide further grazing areas. Use an established aquarium, change water regularly, and keep most mature surface growth. Glass-climbing ability makes a close-fitting lid essential.

Diet & feeding

Wild feeding probably centers on algae and associated microscopic organisms. Prepared foods and live or frozen bloodworms are accepted, but a protein-heavy diet may cause internal problems. Vegetable-rich gel foods containing spirulina can supplement natural growth.

Maintain plentiful soft green algae and diatoms, rotating stones from a separate cultivation container if necessary. Emaciated arrivals need continuous appropriate food with competition removed until their condition improves.

Behaviour & compatibility

Generally peaceful, it needs companions suited to the same stream conditions. Keep at least four; modest conspecific territoriality coexists with an apparent need for company.

Sexual dimorphism

Larger and fuller-bodied individuals may be female. A confirmed external distinction has not been documented.

Breeding

Captive spawning has succeeded, initially under an identification of Erromyzon sinensis. A male defended a site, commonly beside a near-vertical rock face. After elaborate courtship and a T-like position, both fish inserted their rear bodies into the gravel, releasing and fertilizing eggs there. Subsequent parental care was absent.

Young hid within the bottom material and avoided light until emerging around 10 mm total length. They received sinking tablets, with daily changes of about 75% during early rearing, although growth remained uneven. That percentage describes the reported trial. Gravel approximately 1.5–3.5 mm across was favored over coarser material.

After three consecutive spawning events, reproduction stopped and the adults eventually died. Excessive temperature was a possible cause, so deliberate overheating is not an indicated breeding step.

Notes

The ER code preserves an unresolved identity. Trade assignments to other hillstream genera have occurred; distinctive markings help compare stock but do not settle its taxonomy.